HTML 3.0                                                       28th March 1995



   INTERNET DRAFT                                 Dave Raggett, W3C

   Expires in six months                          email: <dsr@w3.org>



             HyperText Markup Language Specification Version 3.0



                       <draft-ietf-html-specv3-00.txt>



Status of this Memo



   This document is an Internet draft. Internet drafts are working

   documents of the Internet Engineering Task Force (IETF), its areas

   and its working groups. Note that other groups may also distribute

   working information as Internet drafts. 



   Internet Drafts are draft documents valid for a maximum of six

   months and can be updated, replaced or obsoleted by other documents

   at any time. It is inappropriate to use Internet drafts as reference

   material or to cite them as other than as "work in progress". 



   To learn the current status of any Internet draft please check the

   "lid-abstracts.txt" listing contained in the Internet drafts shadow

   directories on ftp.is.co.za (Africa), nic.nordu.net (Europe),

   munnari.oz.au (Pacific Rim), ds.internic.net (US East coast) or

   ftp.isi.edu (US West coast). Further information about the IETF can

   be found at URL: http://www.cnri.reston.va.us/ 



   Distribution of this document is unlimited. Please send comments to

   the HTML working group (HTML-WG) of the Internet Engineering Task

   Force (IETF) at <html-wg@wg.oclc.org>. Discussions of this group are

   archived at URL: http://www.acl.lanl.gov/HTML-WG/archives.html. 



Abstract



   The HyperText Markup Language (HTML) is a simple markup language

   used to create hypertext documents that are portable from one

   platform to another. HTML documents are SGML documents with generic

   semantics that are appropriate for representing information from a

   wide range of applications. HTML markup can represent hypertext

   news, mail, documentation, and hypermedia; menus of options;

   database query results; simple structured documents with inlined

   graphics and hypertext views of existing bodies of information. 



   This specification defines the capabilities of HTML version 3.0 and

   provides additional capabilities over previous versions such as

   tables, text flow around figures and math. It is backwards

   compatible with HTML 2.0. 



   [Link to Table of Contents]--  













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HTML 3.0                                                       28th March 1995



Table of Contents



   1.  Introduction  ...................................................... 4



       a)  How to participate in refining HTML 3.0  ....................... 4



       b)  HTML 3.0 Overview  ............................................. 4



       c)  Transition strategy from HTML 2.0  ............................. 5



       d)  Design Guidelines for HTML 3.0  ................................ 6



   2.  Understanding HTML and MIME  ....................................... 9



   3.  Understanding HTML and SGML  ...................................... 10



   4.  The Structure of HTML 3.0 Documents  .............................. 15



   5.  The HEAD Element and Related Elements  ............................ 17



   6.  The BODY Elements  ................................................ 24



       a)  Banners  ...................................................... 26



       b)  Divisions  .................................................... 27



       c)  Heading Elements  ............................................. 29



       d)  Paragraphs  ................................................... 33



       e)  Line Breaks  .................................................. 36



       f)  Horizontal Tabs  .............................................. 38



       g)  Hypertext Links  .............................................. 40



       h)  Overview of Character-Level Elements  ......................... 44



           -   Information Type Elements  ................................ 46



           -   Font Style Elements  ...................................... 48



       i)  The IMG (Image) Element  ...................................... 50



       j)  Unordered Lists  .............................................. 53



       k)  Ordered Lists  ................................................ 59



       l)  Definition Lists  ............................................. 62



       m)  Figures  ...................................................... 69



       n)  Tables  ....................................................... 77



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       o)  Math -- missing entity names --  .............................. 92



       p)  Horizontal Rules  ............................................ 111



       q)  Preformatted Text  ........................................... 113



       r)  Admonishments  ............................................... 116



       s)  Footnotes  ................................................... 118



       t)  Block Quotes  ................................................ 120



       u)  The ADDRESS Element  ......................................... 122



       v)  Fill-out Forms  .............................................. 124



   7.  Special Characters  .............................................. 142



   8.  Security Considerations  ......................................... 145



   9.  HTML 3.0 Document Type Definition 



       a)  The SGML Declaration  ........................................ 146



       b)  The Latin-1 Character Entities -- needs work  ................ 148



       c)  Math and Greek Entities -- under construction  ............... 154



       d)  HTML Icon Entities  .......................................... 156



       e)  The HTML 3.0 DTD  ............................................ 157



   10. Terms -- needs work  ............................................. 185



   11. References -- needs work  ........................................ 188



   12. Acknowledgements -- needs work  .................................. 189

































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HTML 3.0                                                       28th March 1995



Introduction to HTML 3.0



   HyperText Markup Language (HTML) is a simple markup system used to

   create hypertext documents that are portable from one platform to

   another. HTML documents are SGML documents with generic semantics

   that are appropriate for representing information from a wide range

   of applications. HTML markup can represent hypertext news, mail,

   documentation, and hypermedia; menus of options; database query

   results; simple structured documents with in-lined graphics; and

   hypertext views of existing bodies of information. 



   HTML has been in use by the World-Wide Web (WWW) global information

   initiative since 1990. The HTML 3.0 specification provides a number

   of new features, and is broadly backwards compatible with HTML 2.0.

   It is defined as an application of International Standard ISO

   ISO8879:1986 Standard Generalized Markup Language (SGML). This

   specificiation will be proposed as the Internet Media Type (RFC

   1590) and MIME Content Type (RFC 1521) called "text/html;

   version=3.0". 



How to participate in refining HTML 3.0



   The process of refining HTML 3.0 into a formal standard will be

   carried out by the IETF HTML working group. The World Wide Web

   Organization is continuing to develop a freeware testbed browser for

   HTML 3.0 ("Arena") to encourage people to try out the proposed

   features. The discussion list for HTML 3.0 is www-html with html-wg

   reserved for use by the IETF working group for detailed matters

   relating to the formal specification. The process for developing

   HTML 3.0 is open, and anyone who is interested and able to

   contribute to this effort is welcome to join in. 



   --Note: make mailing list names into hypertext links to their

   archives and add info on how to join these lists-- 



HTML 3.0 Overview



   HTML 3.0 builds upon HTML 2.0 and provides full backwards

   compatibility. Tables have been one of the most requested features,

   with text flow around figures and math as runners up. Traditional

   SGML table models, e.g. the CALS table model, are really complex.

   The HTML 3.0 proposal for tables uses a lightweight style of markup

   suitable for rendering on a very wide range of output devices,

   including braille and speech synthesizers. 



   HTML 3.0 introduces a new element: FIG for inline figures. This

   provides for client-side handling of hotzones while cleanly catering

   for non-graphical browsers. Text can be flowed around figures and

   you can control when to break the flow to begin a new element. 



   Including support for equations and formulae in HTML 3.0 adds

   relatively little complexity to a browser. The proposed format is

   strongly influenced by TeX. Like tables, the format uses a



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   lightweight style of markup - simple enough to type in by hand,

   although it will in most cases be easier to use a filter from a word

   processing format or a direct HTML 3.0 wysiwyg editor. The level of

   support is compatible with most word processing software, and avoids

   the drawbacks from having to convert math to inline images. 



   The Web has acted as a huge exercise in user testing, and we have

   been able to glean lots of information from the ways people abuse

   HTML in trying to get a particular effect; as well as from explicit

   demand for new features. HTML 3.0, as a result, includes support for

   customised lists; fine positioning control with entities like

   &emspace; horizontal tabs and horizontal alignment of headers and

   paragraph text. 



   Additional features include a static banner area for corporate

   logos, disclaimers and customized navigation/search controls. The

   LINK element can be used to provide standard toolbar/menu items for

   navigation, such as previous and next buttons. The NOTE element is

   used for admonishments such as notes, cautions or warnings, and also

   used for footnotes. 



   Forms have been extended to support graphical selection menus with

   client-side handling of events similar to FIG. Other new form field

   types include range controls, scribble on image, file upload and

   audio input fields. Client-side scripting of forms is envisaged with

   the script attribute of the FORM element. Forms and tables make for

   a powerful combination offering rich opportunities for laying out

   custom interfaces to remote information systems. 



   To counter the temptation to add yet more presentation features,

   HTML 3.0 is designed (but doesn't require) to be used together with

   style sheets which give rich control over document rendering, and

   can take into account the user's preferences, the window size and

   other resource limitations, such as which fonts are actually

   available. This work will eventually lead to smart layout under the

   author's control, with rich magazine style layouts for full screen

   viewing, switching to simpler layouts when the window is shrunk. 



   The SGML Open consortium is promoting use of DSSSL Lite by James

   Clark. This is a simplified subset of DSSSL - the document style

   semantics specification language. DSSSL is a ISO standard for

   representing presentation semantics for SGML documents, but is much

   too complex in its entirety to be well suited to the World Wide Web.

   Håkon Lie maintains a list of pointers to work on style sheets. 



Transition Strategy from HTML 2.0



   The use of the MIME content type: "text/html; version=3.0" is

   recommended to prevent existing HTML 2.0 user agents screwing up by

   attempting to show 3.0 documents. Tests have shown that the

   suggested content type will safely cause existing user agents to

   display the save to file dialog rather than incorrectly displaying

   the document as if it were HTML 2.0. 



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   To make it easy for servers to distinguish 3.0 documents from 2.0

   documents, it is suggested that 3.0 files are saved with the

   extension ".html3" (or ".ht3" for PCs). Servers can also exploit the

   accept headers in HTTP requests from HTML user agents, to

   distinguish whether each client can or cannot support HTML 3.0. This

   makes it practical for information providers to start providing HTML

   3.0 versions of existing documents for newer user agents, without

   impacting older user agents. It is envisaged that programs will be

   made available for automatic down conversion of 3.0 to 2.0

   documents. This conversion could be carried out in batch mode, or on

   the fly (with caching for greater efficiency). 



Design Guidelines



   The HTML 3.0 draft specification has been written to the following

   guidelines. 



Lingua Franca for the Web



   HTML is intended as a common medium for tying together information

   from widely different sources. A means to rise above the

   interoperability problems with existing document formats, and a

   means to provide a truly open interface to proprietary information

   systems. 



Simplicity



   The first version of HTML was designed to be extremely simple, both

   to author and to write browsers for. This has played a major role in

   the incredibly rapid growth of the World Wide Web. HTML 3.0 provides

   a clean superset of HTML 2.0 adding high value features such as

   tables, text flow around figures and math, while still remaining a

   simple document format. The pressures to adopt the complexities of

   traditional SGML applications has been resisted, for example the

   Department of Defense's CALS table model or the ISO 12083 math DTD. 



Scaleability



   As time goes by, people's expectations change, and more will be

   demanded of HTML. One manifestation of this is the pressure to add

   yet more tags. HTML 3.0 introduces a means for subclassing elements

   in an open-ended way. This can be used to distinguish the role of a

   paragraph element as being a couplet in a stansa, or a mathematical

   term as being a tensor. This ability to make fresh distinctions can

   be exploited to impart distinct rendering styles or to support

   richer search mechanisms, without further complicating the HTML

   document format itself. Scaleability is also achieved via URI based

   links for embedding information in other formats. Initially limited

   to a few image formats, inline support is expected to rapidly evolve

   to cover drawing formats, video, distributed virtual reality and a

   general means for embedding other applications. 





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HTML 3.0                                                       28th March 1995



Platform Independence



   HTML is designed to allow rendering on a very wide range of devices,

   from clunky teletypes, to terminals, DOS, Windows, Macs and high end

   Workstations, as well as non-visual media such as speech and

   braille. In this, it allows users to exploit the legacy of older

   equipment as well as the latest and best of new machines. HTML 3.0

   provides for improved support for non-graphical clients, allowing

   for rich markup in place of the figures shown on graphical clients.

   HTML can be rendered on a wide variety of screen sizes, using a

   scrolling or paged model. The fonts and presentation can be adjusted

   to suit the resources available in the host machine and the user's

   preferences. 



Content --not-- Presentation Markup



   Information providers are used to tight control over the final

   appearence of documents. The need for platform independence weighs

   against this, but there is still a strong pressure to find

   appropriate means for information providers to express their

   intentions. The experience with proprietary document formats has

   shown the dangers of mixing presentation markup with content (or

   structural) markup. It becomes difficult to apply different

   presentation styles. It becomes painful to incorporate material from

   different sources (with different presentation styles). It becomes

   difficult to be truly platform independent. As a result, HTML 3.0 is

   designed for use with linked style information that defines the

   intended presentation style for each element. Style sheets can be

   expressed in a platform independent fashion or used to provide more

   detailed control for particular classes of clients or output media. 



Support for Cascaded Style Sheets



   For the Web, it is valuable to allow for a cascading of style

   preferences. The client has certain built-in preferences; the

   publisher may require a particular house style, e.g. for brand

   distinction; the author may feel the need to override the house

   style for special cases; the end-user may feel strongly about

   certain things, e.g. large fonts for easier visibility or avoiding

   certain colors due to an inability to distinguish between them. HTML

   3.0 supports style sheets via the use of the LINK element to

   reference a style sheet with a URI. Authors can place overrides in

   separate style sheets or include them in the document head within

   the STYLE element. The effectiveness of caching mechanisms for

   speeding up the retrieval of style sheets is enhanced by the

   separation of style information into generic commonly used style

   sheets, and overrides specific to this document. 



Support for Non-Visual Media



   HTML 3.0 is designed to cater for the needs of the visually

   impaired. Markup for inline figures includes support for rich

   descriptions, along with hypertext links that double up as defining



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   geometric hotzones for graphical browsers, simplifying the author's

   job in catering for the different groups of users. Table markup

   includes provision for abbreviated row and column names for each

   cell, which are essential for conversion to speech or braille. Math

   markup treats formulae and equations as hierarchies of expressions.

   This allows disambiguating pauses to be inserted in appropriate

   places during conversion to speech. 



Support for different ways of creating HTML



   HTML 3.0 has been designed to be created in a variety of different

   ways. It is deliberately simple enough to type in by hand. It can be

   authored using wysiwyg editors for HTML, or it can be generated via

   export filters from common word processing formats, or other SGML

   applications.  















































































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Understanding HTML and MIME



   --I have dropped the differentiation of HTML into a sequence of

   conformance levels. Many people confused levels with versions. The

   different levels also encourage interoperability problems! Lets

   encourage full conformance with HTML 2.0 or HTML 3.0 rather than

   perpetuating intermediate levels of support.-- 



HTML as an Internet Media Type



   This (and upward compatible specifications) define the Internet

   Media Type (RFC 1590) and MIME Content Type (RFC 1521) called

   "text/html". The type "text/html" accepts the following parameters: 



   Version 

       To help avoid future compatibility problems, the version

       parameter may be used to give the version number of the

       specification to which the document conforms. The version number

       appears at the front of this document and within the public

       identifier for the SGML DTD. This specification defines version

       3.0. 



   Character sets 

       The charset parameter (as defined in section 7.1.1 of RFC 1521)

       may be used with the text/html content type to specify the

       encoding used to represent the HTML document as a sequence of

       bytes. Normally, text/* media types specify a default of

       US-ASCII for the charset parameter. However, for text/html, if

       the byte stream contains data that is not in the 7-bit US-ASCII

       set, the HTML interpreting agent should assume a default charset

       of ISO-8859-1. 



       When an HTML document is encoded using US-ASCII, the mechanisms

       of numeric character references and character entity references

       may be used to encode additional characters from ISO-8859-1.

       Character entity references are needed for symbols such as math

       and greek characters from other unspecified character sets. 



       Other values for the charset parameter are not defined in this

       specification, but may be specified in future versions of HTML.

       It is envisioned that HTML will use the charset parameter to

       allow support for non-Latin characters such as Arabic, Hebrew,

       Cyrillic and Japanese, rather than relying on any SGML mechanism

       for doing so. 



       --What about Unicode and its assorted encodings? This section

       would benefit from an explanation of the issues underlying

       support for multiple character sets and the problems arising

       from bidirectionality.-- 











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HTML 3.0                                                       28th March 1995



Understanding HTML and SGML



   HTML is an application conforming to International Standard ISO 8879

   -- Standard Generalized Markup Language (SGML). SGML is a system for

   defining structured document types, and markup languages to

   represent instances of those document types. The SGML declaration

   for HTML is given in SGML Declaration for HTML. It is implicit among

   WWW implementations. 



   In the event of any apparent conflict between HTML and SGML

   standards, the SGML standard is definitive. 



   Every SGML document has three parts: 



   SGML declaration 

       Binds SGML processing quantities and syntax token names to

       specific values. For example, the SGML declaration in the HTML

       DTD specifies that the string that opens an end tag is </ and

       the maximum length of a name is 72 characters. 



   Prologue 

       Includes one or more document type declarations (DTDs), which

       specify the element types, element relationships and attributes.

       The HTML 3.0 DTD provides a definitive specification of the

       allowed syntax for HTML 3.0 documents. 



   References 

       Can be represented by markup. An instance, which contains the

       data and markup of the document. 



   HTML refers to the document type as well as the markup language for

   representing instances of that document type. 



------------------------------------------------------------------------------

Understanding HTML Elements



   In HTML documents, tags define the start and end of headings,

   paragraphs, lists, character highlighting and links. Most HTML

   elements are identified in a document as a start tag, which gives

   the element name and attributes, followed by the content, followed

   by the end tag. Start tags are delimited by < and >, and end tags

   are delimited by </ and >. For example: 



       <H1>This is a Heading</H1>

       <P>This is a paragraph.



   Some elements appear as just a start tag. For example, to create a

   line break, you use <BR>. Additionally, the end tags of some other

   elements (e.g. P, LI, DT, DD) can be omitted as the position of the

   end tag is clearly implied by the context. 



   The content of an element is a sequence of characters and nested

   elements. Some elements, such as anchors, cannot be nested. Anchors



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HTML 3.0                                                       28th March 1995



   and character highlighting may be put inside other constructs. The

   content model for a tag defines the syntax permitted for the

   content. 



   Note: The SGML declaration for HTML specifies SHORTTAG YES, which

   means that there are other valid syntaxes for tags, such as NET

   tags, <EM/.../; empty start tags, <>; and empty end tags, </>. Until

   support for these idioms is widely deployed, their use is strongly

   discouraged. 



------------------------------------------------------------------------------

Names



   The element name immediately follows the tag open delimiter. An

   element name consist of a letter followed by up to 72 letters,

   digits, periods, or hyphens. Names are not case sensitive. For

   example, H1 is equivalent to h1. This limit of 72 characters is set

   by the NAMELEN parameter in the SGML declaration for HTML 3.0. 



------------------------------------------------------------------------------

Attributes



   In a start tag, white space and attributes are allowed between the

   element name and the closing delimiter. An attribute typically

   consists of an attribute name, an equal sign, and a value (although

   some attributes may be just a value). White space is allowed around

   the equal sign. 



   The value of the attribute may be either: 



   1.  A string literal, delimited by single quotes or double quotes 



   2.  A name token (a sequence of letters, digits, periods, or

       hyphens) 



   In this example, a is the element name, href is the attribute name,

   and http://host/dir/file.html is the attribute value: 



       <A HREF="http://host/dir/file.html">



   Some implementations consider any occurrence of the > character to

   signal the end of a tag. For compatibility with such

   implementations, when > appears in an attribute value, you may want

   to represent it with an entity or numeric character reference, such

   as: 



       <IMG SRC="eq1.ps" alt="a &#62; b">



   To put quotes inside of quotes, you can use single quotes if the

   outer quotes are double or vice versa, as in: 



       <IMG SRC="image.ps" alt="First 'real' example">





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   Alternatively, you use the character representation &quot; as in: 



       <IMG SRC="image.ps" alt="First &quot;real&quot; example">



   The length of an attribute value (after replacing entity and numeric

   character references) is limited to 1024 characters. This number is

   defined by the LITLEN parameter in the SGML declaration for HTML

   3.0. 



   Note: Some implementations allow any character except space or > in

   a name token. Attributes values must be quoted only if they don't

   satisfy the syntax for a name token. 



   Attributes with a declared value of NAME (e.g. ISMAP, COMPACT) may

   be written using a minimized syntax. The markup: 



       <UL COMPACT="compact">



   can be written as: 



       <UL COMPACT>



   Note: Unless you use the minimized syntax, some implementations

   won't understand. 



------------------------------------------------------------------------------

Undefined Tag and Attribute Names



   It is an accepted networking principle to be conservative in that

   which one produces, and liberal in that which one accepts. HTML

   parsers should be liberal except when verifying code. HTML

   generators should generate strictly conforming HTML. It is suggested

   that where ever practical, parsers should at least flag the presence

   of markup errors, as this will help to avoid bad markup being

   produced inadvertently. 



   The behavior of WWW applications reading HTML documents and

   discovering tag or attribute names which they do not understand

   should be to behave as though, in the case of a tag, the whole tag

   had not been there but its content had, or in the case of an

   attribute, that the attribute had not been present. 



------------------------------------------------------------------------------

Special Characters



   The characters between the tags represent text in the ISO-Latin-1

   character set, which is a superset of ASCII. Because certain

   characters will be interpreted as markup, they should be represented

   by markup -- entity or numeric character references, for instance

   the character "&" must be represented by the entity &amp;. See the

   Special Characters section of this specification for more

   information. 





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------------------------------------------------------------------------------

Comments



   To include comments in an HTML document that will be ignored by the

   parser, surround them with <!-- and -->. After the comment

   delimiter, all text up to the next occurrence of --> is ignored.

   Hence comments cannot be nested. White space is allowed between the

   closing -- and >, but not between the opening <! and --. 



   For example: 



   <HEAD>

   <TITLE>HTML Guide: Recommended Usage</TITLE>

   <!-- Id: Text.html,v 1.6 1994/04/25 17:33:48 connolly Exp -->

   </HEAD>



   Note: Some historical implementations incorrectly consider a > sign

   to terminate a comment. 



------------------------------------------------------------------------------

Formal Variants of HTML 3.0



   The HTML 3.0 document type definition includes two flags for

   controlling how prescriptive or how lax the language is. This makes

   use of SGML marked sections in the DTD to enable or disable certain

   features. 



HTML.Recommended



   Certain features of the language are necessary for compatibility

   with widespread usage, but they may compromise the structural

   integrity of a document. The HTML.Recommended entity should be

   defined as INCLUDE in the DTD subset to enable a more prescriptive

   version of HTML 3.0 that eliminates the above features. For example: 



   <!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 3.0//EN"

   [ <!ENTITY % HTML.Recommended "INCLUDE"> ] >



   In particular, this prevents text from appearing except within block

   elements. 



HTML.Deprecated



   By default, for backwards compatibility, the %HTML.Deprecated entity

   is defined as INCLUDE, enabling certain features which are now

   deprecated. These features can be eliminated by defining this entity

   as IGNORE in the DTD subset. For example: 



       <!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 3.0//EN" [

   <!ENTITY % HTML.Deprecated "IGNORE"> ] >



   Note: defining %HTML.Recommended as INCLUDE automatically sets

   %HTML.Deprecated to IGNORE. 



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   In the spirit of being liberal in what you accept and strict in what

   you generate, HTML user agents are recommended to accept syntax

   corresponding to the specification with %HTML.Deprecated turned on,

   while HTML user agents generating HTML are recommended to generate

   documents that conform to the specification with %HTML.Recommended

   turned on.  































































































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HTML 3.0                                                       28th March 1995



The Structure of HTML 3.0 Documents



   In HTML documents, tags define the start and end of headings,

   paragraphs, lists, character highlighting and links etc. Most HTML

   elements are identified in a document as a start tag, which gives

   the element name and attributes, followed by the content, followed

   by the end tag. Start tags are delimited by < and >, while end tags

   are delimited by </ and >. For example: 



       <title>This is a Title</title>

       <h1>This is a Heading</h1>

       <P>This is a paragraph.



   Every HTML document as a minimum must have a title. To identify the

   document as being HTML 3.0, it is recommended that documents start

   with the prologue: 



       <!doctype HTML public "-//W3O//DTD W3 HTML 3.0//EN">



   When absent, this prologue is implied by the MIME content type for

   HTML 3.0 together with the associated version parameter. 



------------------------------------------------------------------------------

Document Structure



   HTML 3.0 documents formally have the following structure: 



       <HTML>

       <HEAD> --head elements ...--

       <BODY> --body elements ...--

       </HTML>



   In most cases, the HTML, HEAD and BODY tags can be safely omitted.

   Note that the formal syntax of HTML 3.0 is defined by the document

   type definition, which is included as an appendix of this

   specification. The details of the HEAD and BODY elements will be

   described in subsequent sections. 



   The permitted syntax of HTML 3.0 compliant documents is specified by

   the DTD. This includes the content model for each element, defining

   what markup is permitted within each element. The DTD uses SGML

   entities in content models to express regular features of HTML 3.0,

   for example %body.content defines what markup is permitted within

   the BODY element. A number of other elements also share this content

   model, e.g. BQ, DIV, FORM, TH and TD. 



   The description of each tag includes the --content model-- and the

   --permitted context-- (which elements can contain this tag). Where

   practical, these properties are given with the same entity names as

   used in the DTD, and should help the newcomer to get to grips with

   understanding the DTD itself. For example, the description of the

   NOTE element starts with: 





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       The NOTE element

   

       Permitted context: %block

       Content model: %flow



   This says that the NOTE element (used for admonishments such as

   notes, cautions and errors) can occur in any element which includes

   %block in its content model. Similarly, any element with %flow as

   part of its permitted context can occur within a NOTE element. 



The HTML element



   This has three attributes: 



   VERSION 

       This is fixed by the DTD as the string "-//W3O//DTD W3 HTML

       3.0//EN" 



   URN 

       The universal resource name for the document (optional) 



   ROLE 

       An optional space separated list of SGML NAME tokens that define

       the role this document plays, e.g. table of contents. The

       conventions for these names are outside the scope of this

       specification. --wouldn't it be better to leave this to a link

       to a URC?-- 



   Note that both the start and end tag for the HTML element can be

   omitted.  

















































Dave Raggett                                                           Page 16



HTML 3.0                                                       28th March 1995



The Head Element and Related Elements



HEAD



   The HEAD element has no attributes and the start and end tag can

   always be safely omitted as they can be readily inferred by the

   parser. Information in the HEAD element corresponds to the top part

   of a memo or mail message. It describes properties of the document

   such as the title, the document toolbar, and additional

   meta-information. There is no intended significance to the order of

   elements in the document head. Note that the TITLE element is always

   required. In fact, the minimal HTML 3.0 document consists of the

   TITLE element alone! 



   Within the HEAD element, only certain elements are allowed.

   Information in the HEAD element may include the following elements

   (arranged alphabetically): 



------------------------------------------------------------------------------

BASE



   The BASE element allows the URL of the document itself to be

   recorded in situations in which the document may be read out of

   context. URLs within the document may be in a "partial" form

   relative to this base address. The default base address is the URL

   used to retrieve the document. 



   For example: 



       <base href="http://acme.com/docs/mydoc.html">

       ... 

       <img src="images/me.gif">



   which resolves to "http://acme.com/docs/images/me.gif". 



------------------------------------------------------------------------------

ISINDEX



   The ISINDEX element informs the HTML user agent that the document is

   an index document. As well as reading it, the reader may use a

   keyword search. 



   The document can be queried with a keyword search by adding a

   question mark to the end of the document address, followed by a list

   of keywords separated by plus signs. See the network address format

   for more information. 



   Note: A server normally generates the ISINDEX tag automatically. If

   added by hand to an HTML document, the browser assumes that the

   server can handle a search on the document. Obviously the server

   must have this capability for it to work: simply adding <ISINDEX> in

   the document is not enough to make searches happen if the server

   does not have a search engine! 



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   Example: 



       <ISINDEX>



   The URL used for processing queries can be overridden with the HREF

   attribute. You can also use the PROMPT attribute to change the

   default prompt supplied by the browser, e.g. 



       <ISINDEX HREF="phone.db" PROMPT="Enter Surname:">



------------------------------------------------------------------------------

LINK



   The LINK element indicates a relationship between the document and

   some other object. A document may have any number of LINK elements.

   The LINK element is empty (does not have a closing tag), but takes

   the same attributes as the anchor element. The important attributes

   are: 



   REL 

       This defines the relationship defined by the link. 



   REV 

       This defines a reverse relationship. A link from document A to

       document B with REV=--relation-- expresses the same relationship

       as a link from B to A with REL=--relation--. REV=made is

       sometimes used to identify the document author, either the

       author's email address with a --mailto-- URI, or a link to the

       author's home page. 



   HREF 

       This names an object using the URI notation. 



Using LINK to define document specific toolbars



   An important use of the LINK element is to define a toolbar of

   navigation buttons or an equivalent mechanism such as menu items. 



   LINK relationship values reserved for toolbars are: 



   REL=Home 

       The link references a home page or the top of some hierarchy. 



   REL=ToC 

       The link references a document serving as a table of contents. 



   REL=Index 

       The link references a document providing an index for the

       current document. 



   REL=Glossary 

       The link references a document providing a glossary of terms



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       that pertain to the current document. 



   REL=Copyright 

       The link references a copyright statement for the current

       document. 



   REL=Up 

       When the document forms part of a hierarchy, this link

       references the immediate parent of the current document. 



   REL=Next 

       The link references the next document to visit in a guided tour. 



   REL=Previous 

       The link references the previous document in a guided tour. 



   REL=Help 

       The link references a document offering help, e.g. describing

       the wider context and offering further links to relevant

       documents. This is aimed at reorienting users who have lost

       their way. 



   REL=Bookmark 

       Bookmarks are used to provide direct links to key entry points

       into an extended document. The TITLE attribute may be used to

       label the bookmark. Several bookmarks may be defined in each

       document, and provide a means for orienting users in extended

       documents. 



   An example of toolbar LINK elements: 



       <LINK REL=Previous HREF=doc31.html>

       <LINK REL=Next HREF=doc33.html>

       <LINK REL=Bookmark TITLE="Order Form" HREF=doc56.html>



Using LINK to include a Document Banner



   The LINK element can be used with REL=Banner to reference another

   document to be used as banner for this document. This is typically

   used for corporate logos, navigation aids, and other information

   which shouldn't be scrolled with the rest of the document. For

   example: 



       <LINK REL=Banner HREF=banner.html>



   The use of a LINK element in this way, allows a banner to be shared

   between several documents, with the benefit of being able to

   separately cache the banner. Rather than using a linked banner, you

   can also include the banner in the document itself, using the BANNER

   element. 



Link to an associated Style Sheet





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   The LINK element can be used with REL=StyleSheet to reference a

   style sheet to be used to control the way the current document is

   rendered. For example: 



       <LINK REL=StyleSheet HREF=housestyle.dsssl>



Other uses of the LINK element



   Additional relationship names have been proposed, but do not form

   part of this specification. Servers may also allow links to be added

   by those who do not have the right to alter the body of a document. 



------------------------------------------------------------------------------

META



   The META element is used within the HEAD element to embed document

   meta-information not defined by other HTML elements. Such

   information can be extracted by servers/clients for use in

   identifying, indexing and cataloging specialized document

   meta-information. 



   Although it is generally preferable to used named elements that have

   well defined semantics for each type of meta-information, such as

   title, this element is provided for situations where strict SGML

   parsing is necessary and the local DTD is not extensible. 



   In addition, HTTP servers can read the contents of the document head

   to generate response headers corresponding to any elements defining

   a value for the attribute HTTP-EQUIV. This provides document authors

   with a mechanism (not necessarily the preferred one) for identifying

   information that should be included in the response headers of an

   HTTP request. 



   The META element has three attributes: 



   NAME 

       Used to name a property such as author, publication date etc. If

       absent, the name can be assumed to be the same as the value of

       HTTP-EQUIV. 



   CONTENT 

       Used to supply a value for a named property. 



   HTTP-EQUIV 

       This attribute binds the element to an HTTP response header. If

       the semantics of the HTTP response header named by this

       attribute is known, then the contents can be processed based on

       a well defined syntactic mapping, whether or not the DTD

       includes anything about it. HTTP header names are not case

       sensitive. If absent, the NAME attribute should be used to

       identify this meta-information and it should not be used within

       an HTPP response header. 





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   Examples: 



   If the document contains: 



   <META HTTP-EQUIV=Expires CONTENT="Tue, 04 Dec 1993 21:29:02 GMT">

   <META HTTP-EQUIV="Keywords" CONTENT="Nanotechnology, Biochemistry">

   <META HTTP-EQUIV="Reply-to" CONTENT="dsr@w3.org (Dave Raggett)">

   



   The server will include the following response headers: 



   Expires: Tue, 04 Dec 1993 21:29:02 GMT

   Keywords: Nanotechnology, Biochemistry

   Reply-to: dsr@w3.org (Dave Raggett)



   When the HTTP-EQUIV attribute is absent, the server should not

   generate an HTTP response header for this meta-information, e.g. 



   <META NAME="IndexType" CONTENT="Service">



   Do not use the META element to define information that should be

   associated with an existing HTML element. 



   Example of an inappropriate use of the META element: 



   <META NAME="Title" CONTENT="The Etymology of Dunsel">



   Do not name an HTTP-EQUIV attribute the same as a response header

   that should typically only be generated by the HTTP server. Some

   inappropriate names are "Server", "Date", and "Last-Modified".

   Whether a name is inappropriate depends on the particular server

   implementation. It is recommended that servers ignore any META

   elements that specify HTTP equivalents (case insensitively) to their

   own reserved response headers. 



------------------------------------------------------------------------------

NEXTID



   The NEXTID is a parameter read and generated by text editing

   software to generate unique identifiers. This tag takes a single

   attribute which is the the next document-wide alpha-numeric

   identifier to be allocated of the form z123. 



   When modifying a document, existing anchor identifiers should not be

   reused, as these identifiers may be referenced by other documents.

   Human writers of HTML usually use mnemonic alphabetical identifiers. 



   Example: 



       <NEXTID N=Z27>



   HTML user agents may ignore the NEXTID element. Support for NEXTID

   does not impact HTML user agents in any way. 



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HTML 3.0                                                       28th March 1995





   --I want to get rid of NEXTID, or at least deprecate it!-- 



------------------------------------------------------------------------------

RANGE



   The RANGE element is used to mark a range of the document, for

   example for highlighting regions of the document matching some

   search criteria, or which are the subject of an annotation etc. 



       <RANGE CLASS=Search FROM=spot01 UNTIL=spot02>



   The FROM and UNTIL attributes specify positions in the document

   using SGML identifiers. Most elements in the document body can

   define such identifiers using ID attributes. The SPOT element is

   useful in this regard, as it allows search software etc. to insert

   IDs at random places: 



       <SPOT ID=spot01> ... <SPOT ID=spot02>



   The RANGE element supports the following attributes: 



   ID

       An SGML identifer used to name the range element. 



   CLASS

       A character string used to subclass the range element. 



   FROM

       References an SGML identifier for an element in the document

       body. It identifies the start of the marked range. 



   UNTIL

       References an SGML identifier for an element in the document

       body. It identifies the end of the marked range. 



------------------------------------------------------------------------------

STYLE



   The STYLE element provides a means for including rendering

   information using a specified style notation. Information in the

   STYLE element overrides client defaults and that of linked style

   sheets. It allows authors to specify overrides, while for the most

   part using a generic style sheet, and as such improves the

   effectiveness of caching schemes for linked style sheets. There is

   one attribute - NOTATATION - which specifies an entity identifying

   an SGML notation in the HTML 3.0 DTD, for example: 



       <style notation=dsssl-lite>

         --some dsssl-lite stuff ...--

       </style>



   Stylistic rules will in general match tag names and attribute values



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HTML 3.0                                                       28th March 1995



   for elements in the document body. Context sensitive rules may be

   used for such purposes as rendering drop down capitals for the

   initial letter in the first paragraph following a header. 



------------------------------------------------------------------------------

TITLE



   Every HTML document must contain a TITLE element. The title should

   identify the contents of the document in a global context, and may

   be used in a history lists and as a label for the window displaying

   the document. Unlike headings, titles are not normally displayed in

   the text of a document itself. 



   The TITLE element must occur within the head of the document, and

   may not contain anchors, paragraph tags, or highlighting. There may

   only be one TITLE in any document. 



   The length of titles is unlimited, however, long titles may be

   truncated in some applications. To minimize this possibility, keep

   titles to fewer than 64 characters. Also keep in mind that a short

   title, such as Introduction, may be meaningless out of context. An

   example of a meaningful title might be: 



       <Title>Recent Advances in Nanotechnology</Title>





























































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HTML 3.0                                                       28th March 1995



The Body Element and Related Elements



The BODY element



   Permitted Context: HTML

   Content Model: %Body.Content 



   Within the BODY element, you can structure text into paragraphs, and

   lists, as well as highlighting phrases and creating links, amongst

   other things. The BODY element has the following attributes, all of

   which are optional: 



   Note that the ID, LANG and CLASS attributes can be used with

   virtually all of the elements permitted in the document body. 



   ID 

       An SGML identifier used as the target for hypertext links or for

       naming particular elements in associated style sheets.

       Identifiers are NAME tokens and must be unique within the scope

       of the current document. 



   LANG 

       This is one of the ISO standard language abbreviations, e.g.

       "en.uk" for the variation of English spoken in the United

       Kingdom. It can be used by parsers to select language specific

       choices for quotation marks, ligatures and hypenation rules etc.

       The language attribute is composed from the two letter language

       code from ISO 639, optionally followed by a period and a two

       letter country code from ISO 3166. 



   CLASS 

       This a space separated list of SGML NAME tokens and is used to

       subclass tag names. For instance, <P CLASS=STANZA.COUPLET>

       defines a paragraph that acts as a couplet in a stanza. By

       convention, the class names are interpreted hierarchically, with

       the most general class on the left and the most specific on the

       right, where classes are separated by a period. The CLASS

       attribute is most commonly used to attach a different style to

       some element, but it is recommended that where practical class

       names should be picked on the basis of the element's semantics,

       as this will permit other uses, such as restricting search

       through documents by matching on element class names. The

       conventions for choosing class names are outside the scope of

       this specification. 



   BACKGROUND 

       This can be used to specify a URI for an image tile to cover the

       document background. This provides a way of giving a group of

       documents a distinctive appearence. Clients may ignore this

       attribute. It is included here for the benefit of clients that

       don't support style sheets. Note that the text color may need to

       be adjusted to show an adequate contrast with the background. 





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   Note that you don't need to include a BODY tag unless you want to

   specify one of the above attributes. 



Body Structure



   The document body is composed from zero or more of the following

   elements: 



   *   DIV - used for hierarchical containers and static banners 



   *   Headings (H1, to H6) - a set of headers of varying levels of

       importance 



   *   Block elements - paragraphs, lists, forms, tables, figures and

       other elements 



   *   Horizontal rules, and the ADDRESS element 



   *   Text and character level markup including emphasis, images,

       math, hypertext links and miscellaneous elements. 



   Note that text and character level markup are only permitted at this

   level for backwards compatibility with legacy documents. The

   HTML.Recommended flag enforces a more structured approach to

   authoring HTML documents.  



























































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HTML 3.0                                                       28th March 1995



Banners



   Permitted Context: the start of the BODY element

   Content Model: %Body.Content 



   The BANNER element is used for corporate logos, navigation aids,

   disclaimers and other information which shouldn't be scrolled with

   the rest of the document. It provides an alternative to using the

   LINKelement in the document head to reference an externally defined

   banner. 



Permitted Attributes



   ID 

       An SGML identifier used as the target for hypertext links or for

       naming particular elements in associated style sheets.

       Identifiers are NAME tokens and must be unique within the scope

       of the current document. 



   LANG 

       This is one of the ISO standard language abbreviations, e.g.

       "en.uk" for the variation of English spoken in the United

       Kingdom. It can be used by parsers to select language specific

       choices for quotation marks, ligatures and hypenation rules etc.

       The language attribute is composed from the two letter language

       code from ISO 639, optionally followed by a period and a two

       letter country code from ISO 3166. 



   CLASS 

       This a space separated list of SGML NAME tokens and is used to

       subclass tag names. By convention, the class names are

       interpreted hierarchically, with the most general class on the

       left and the most specific on the right, where classes are

       separated by a period. The CLASS attribute is most commonly used

       to attach a different style to some element, but it is

       recommended that where practical class names should be picked on

       the basis of the element's semantics, as this will permit other

       uses, such as restricting search through documents by matching

       on element class names. The conventions for choosing class names

       are outside the scope of this specification. 





























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HTML 3.0                                                       28th March 1995



Divisions



   Permitted Context: %Body.Content

   Content Model: %Body.Content 



   The DIV element is used with the CLASS attribute to represent

   different kinds of containers, e.g. chapter, section, abstract, or

   appendix. For example: 



   <DIV CLASS=Abstract>

   <P>TheChieftain product range is the white hot hope for the

   coming year. This report sets out how to position Chieftain

   against competing products.

   </DIV>



Permitted Attributes



   ID 

       An SGML identifier used as the target for hypertext links or for

       naming particular elements in associated style sheets.

       Identifiers are NAME tokens and must be unique within the scope

       of the current document. 



   LANG 

       This is one of the ISO standard language abbreviations, e.g.

       "en.uk" for the variation of English spoken in the United

       Kingdom. It can be used by parsers to select language specific

       choices for quotation marks, ligatures and hypenation rules etc.

       The language attribute is composed from the two letter language

       code from ISO 639, optionally followed by a period and a two

       letter country code from ISO 3166. 



   CLASS 

       This a space separated list of SGML NAME tokens and is used to

       subclass tag names. For instance, <DIV CLASS=APPENDIX> defines a

       division that acts as an appendix. By convention, the class

       names are interpreted hierarchically, with the most general

       class on the left and the most specific on the right, where

       classes are separated by a period. The CLASS attribute is most

       commonly used to attach a different style to some element, but

       it is recommended that where practical class names should be

       picked on the basis of the element's semantics, as this will

       permit other uses, such as restricting search through documents

       by matching on element class names. The conventions for choosing

       class names are outside the scope of this specification. 



   ALIGN 

       The ALIGN attribute can be used to explicitly specify the

       horizontal alignment of paragraphs within a division:

       

       



       align=left 



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HTML 3.0                                                       28th March 1995



           Paragraphs are rendered flush left (the default). 



       align=center 

           Paragraphs are centered. 



       align=right 

           Paragraphs are rendered flush right. 



       align=justify 

           Text lines are justified where practical, otherwise this

           gives the same effect as the default align=left setting.



   NOWRAP 

       The NOWRAP attribute is used when you don't want the browser to

       automatically wrap lines. You can then explicitly specify line

       breaks in paragrphs using the BR element. 



   CLEAR 

       This attribute is common to all block-like elements. When text

       flows around a figure or table in the margin, you sometimes want

       to start the division below the figure rather than alongside it.

       The CLEAR attribute allows you to move down unconditionally:

       

       



       clear=left

           move down until left margin is clear 



       clear=right

           move down until right margin is clear 



       clear=all

           move down until both margins are clear 



       Alternatively, you can decide to place the element alongside the

       figure just so long as there is enough room. The minimum width

       needed is specified as:

       

       



       clear="40 en"

           move down until there is at least 40 en units free 



       clear="100 pixels"

           move down until there is at least 100 pixels free 



       The style sheet (or browser defaults) may provide default

       minimum widths for each class of block-like elements. 













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HTML 3.0                                                       28th March 1995



Headings



   Permitted Context: %Body.Content

   Content Model: %text 



   HTML defines six levels of headings. A heading element implies all

   the font changes, paragraph breaks before and after, and any white

   space necessary to render the heading. The heading elements are H1,

   H2, H3, H4, H5, and H6 with H1 being the highest (or most important)

   level and H6 the least. For example: 



   <H1>This is a top level heading</H1> Here is some text.

   <H2>Second level heading</H2> Here is some more text.



   Use the DIV element together with header elements when you want to

   make the hierarchical structure of a document explicit. This is

   needed as header elements themselves only contain the text of the

   header, and do not imply any structural division of documents into

   sections. Header elements have the same content model as paragraphs,

   that is text and character level markup, such as character emphasis,

   inline images, form fields and math. 



   Headers play a related role to lists in structuring documents, and

   it is common to number headers or to include a graphic that acts

   like a bullet in lists. HTML 3.0 recognizes this with attributes

   that assist with numbering headers and allow authors to specify a

   custom graphic. 



   The numbering style is controlled by the style sheet, e.g. 



   1.  The style sheet specifies whether headers are numbered, and

       which style is used to render the current sequence number, e.g.

       arabic, upper alpha, lower alpha, upper roman, lower roman or a

       numbering scheme appropriate to the current language. 



   2.  Whether the parent numbering is inherited, e.g. "5.1.d" where 5

       is the current sequence number for H1 headers, 1 is the number

       for H2 headers and 4 for H3 headers. 



   The seqnum and skip attributes can be used to override the default

   treatment of header sequence numbers, and provide for a continuity

   with numbered lists. 



   The dingbat or src attribute may be used to specify a bullet-like

   graphic to be placed adjacent to the header. The positioning of this

   graphic is controlled by the style sheet. The graphic is for

   decorative purposes only and silently ignored on non-graphical HTML

   user agents. 



Word Wrapping



   User agents are free to wrap lines at whitespace characters so as to

   ensure lines fit within the current window size. Use the &nbsp;



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HTML 3.0                                                       28th March 1995



   entity for the non-breaking space character, when you want to make

   sure that a line isn't broken! Alternatively, use the NOWRAP

   attribute to disable word wrapping and the <BR> element to force

   line breaks where desired. 



   --Netscape includes two tags: <NOBR>...</NOBR>, and <WBR>. The

   former turns off wordwrapping between the start and end NOBR tag,

   while WBR is for the rare case when you want to specify where to

   break the line if needed. Should HTML 3.0 provide an equivalent

   mechanism to WBR, (either a tag or an entity)?-- 



Permitted Attributes



   ID 

       An SGML identifier used as the target for hypertext links or for

       naming particular elements in associated style sheets.

       Identifiers are NAME tokens and must be unique within the scope

       of the current document. 



   LANG 

       This is one of the ISO standard language abbreviations, e.g.

       "en.uk" for the variation of English spoken in the United

       Kingdom. It can be used by parsers to select language specific

       choices for quotation marks, ligatures and hypenation rules etc.

       The language attribute is composed from the two letter language

       code from ISO 639, optionally followed by a period and a two

       letter country code from ISO 3166. 



   CLASS 

       This a space separated list of SGML NAME tokens and is used to

       subclass tag names. For instance, <H2 CLASS=Section> defines a

       level 2 header that acts as a section header. By convention, the

       class names are interpreted hierarchically, with the most

       general class on the left and the most specific on the right,

       where classes are separated by a period. The CLASS attribute is

       most commonly used to attach a different style to some element,

       but it is recommended that where practical class names should be

       picked on the basis of the element's semantics, as this will

       permit other uses, such as restricting search through documents

       by matching on element class names. The conventions for choosing

       class names are outside the scope of this specification. 



   ALIGN 

       Headings are usually rendered flush left. The ALIGN attribute

       can be used to explicitly specify the horizontal alignment:

       

       



       align=left 

           The heading is rendered flush left (the default). 



       align=center 

           The heading is centered. 



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HTML 3.0                                                       28th March 1995





       align=right 

           The heading is rendered flush right. 



       align=justify 

           Heading lines are justified where practical, otherwise this

           gives the same effect as the default align=left setting. 



       For example: 



       <h1 align=center>This is a centered heading</H1>

       Here is some text. <H2 align=right>and this is a flush right

       heading</H2> Here is some more text.



   CLEAR 

       This attribute is common to all block-like elements. When text

       flows around a figure or table in the margin, you sometimes want

       to start an element like a header, paragraph or list below the

       figure rather than alongside it. The CLEAR attribute allows you

       to move down unconditionally:

       

       



       clear=left

           move down until left margin is clear 



       clear=right

           move down until right margin is clear 



       clear=all

           move down until both margins are clear 



       Alternatively, you can decide to place the element alongside the

       figure just so long as there is enough room. The minimum width

       needed is specified as:

       

       



       clear="40 en"

           move down until there is at least 40 en units free 



       clear="100 pixels"

           move down until there is at least 100 pixels free 



       The style sheet (or browser defaults) may provide default

       minimum widths for each class of block-like elements. 



   SEQNUM 

       A sequence number is associated with each level of header from

       the top level (H1) to the bottom level (H6). This attribute is

       used to set the sequence number associated with the header level

       of the current element to a given number, e.g. SEQNUM=10.

       Normally, the sequence number is initialized to 1 at the



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HTML 3.0                                                       28th March 1995



       beginning of the document and incremented after each header

       element. It is reset to 1 by any header element of a higher

       level, e.g. an H1 header resets the sequence numbers for H2 to

       H6. The style of header numbering is controlled by the style

       sheet. 



   SKIP 

       Increments the sequence number before rendering the element. It

       is used when headers have been left out of the sequence. For

       instance, SKIP=3 advances the sequence number past 3 omitted

       items. 



   DINGBAT 

       Specifies an iconic image to appear preceding the header. The

       icon is specified as an entity name. A list of standard icon

       entity names for HTML 3.0 is given in an appendix of this

       specification. 



   SRC 

       Specifies an image to appear preceding the header. The image is

       specified as a URI. This attribute may appear together with the

       MD attribute. 



   MD 

       Specifies a message digest or cryptographic checksum for the

       associated graphic specified by the SRC attribute. It is used

       when you want to be sure that a linked object is indeed the same

       one that the author intended, and hasn't been modified in any

       way. For instance, MD="md5:jV2OfH+nnXHU8bnkPAad/mSQlTDZ", which

       specifies an MD5 checksum encoded as a base64 character string.

       The MD attribute is generally allowed for all elements which

       support URI based links. 



   NOWRAP 

       The NOWRAP attribute is used when you don't want the browser to

       automatically wrap lines. You can then explicitly specify line

       breaks in headings using the BR element. For example: 



       <h1 nowrap>This heading has wordwrap turned off<br>

       and the BR element is used for explicit line breaks</H1>





























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Paragraphs



   Permitted Context: %Body.Content, %flow, %block

   Content Model: %text 



   The <P> element is used to define a paragraph. The exact rendering

   (indentation, leading etc.) is not defined and may be a function of

   other tags, style sheets, etc. The ALIGN attribute can be used to

   explicitly specify the horizontal alignment. Paragraph elements have

   the same content model as headers, that is text and character level

   markup, such as character emphasis, inline images, form fields and

   math. 



   Example: 



   <H1>The heading precedes the first paragraph</H1>

   <P>Here is the text of the first paragraph. <P>and this is

   the text of the second paragraph.



   The text up to the next <p> element is treated as being part of the

   current paragraph. This is an example of how SGML allows certain end

   tags like </p> to be left out where they can be inferred from the

   context. 



Word Wrapping



   User agents are free to wrap lines at whitespace characters so as to

   ensure lines fit within the current window size. Use the &nbsp;

   entity for the non-breaking space character, when you want to make

   sure that a line isn't broken! Alternatively, use the NOWRAP

   attribute to disable word wrapping and the <BR> element to force

   line breaks where desired. 



   --Netscape includes two tags: <NOBR>...</NOBR>, and <WBR>. The

   former turns off wordwrapping between the start and end NOBR tag,

   while WBR is for the rare case when you want to specify where to

   break the line if needed. Should HTML 3.0 provide an equivalent

   mechanism to WBR, (either a tag or an entity)?-- 



   Note: Do not use empty paragraphs to add white space around

   headings, lists or other elements. White space is added by the

   rendering software. 



Permitted Attributes



   ID 

       An SGML identifier used as the target for hypertext links or for

       naming particular elements in associated style sheets.

       Identifiers are NAME tokens and must be unique within the scope

       of the current document. 



   LANG 

       This is one of the ISO standard language abbreviations, e.g.



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       "en.uk" for the variation of English spoken in the United

       Kingdom. It can be used by parsers to select language specific

       choices for quotation marks, ligatures and hypenation rules etc.

       The language attribute is composed from the two letter language

       code from ISO 639, optionally followed by a period and a two

       letter country code from ISO 3166. 



   CLASS 

       This a space separated list of SGML NAME tokens and is used to

       subclass tag names. For instance, <P CLASS=abstract> defines a

       paragraph that acts as an abstract. By convention, the class

       names are interpreted hierarchically, with the most general

       class on the left and the most specific on the right, where

       classes are separated by a period. The CLASS attribute is most

       commonly used to attach a different style to some element, but

       it is recommended that where practical class names should be

       picked on the basis of the element's semantics, as this will

       permit other uses, such as restricting search through documents

       by matching on element class names. The conventions for choosing

       class names are outside the scope of this specification. 



   ALIGN 

       Paragraphs are usually rendered flush left. The ALIGN attribute

       can be used to explicitly specify the horizontal alignment:

       

       



       align=left 

           The paragraph is rendered flush left (the default). 



       align=center 

           The paragraph is centered. 



       align=right 

           The paragraph is rendered flush right. 



       align=justify 

           Text lines are justified where practical, otherwise this

           gives the same effect as the default align=left setting.



       For example: 



       <p align=center>This is a centered paragraph.

       <p align=right>and this is a flush right paragraph.



   CLEAR 

       This attribute is common to all block-like elements. When text

       flows around a figure or table in the margin, you sometimes want

       to start an element like a header, paragraph or list below the

       figure rather than alongside it. The CLEAR attribute allows you

       to move down unconditionally:

       

       



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       clear=left

           move down until left margin is clear 



       clear=right

           move down until right margin is clear 



       clear=all

           move down until both margins are clear 



       Alternatively, you can decide to place the element alongside the

       figure just so long as there is enough room. The minimum width

       needed is specified as:



       clear="40 en"

           move down until there is at least 40 en units free 



       clear="100 pixels"

           move down until there is at least 100 pixels free 



       The style sheet (or browser defaults) may provide default

       minimum widths for each class of block-like elements. 



   NOWRAP 

       The NOWRAP attribute is used when you don't want the browser to

       automatically wrap lines. You can then explicitly specify line

       breaks in paragraphs using the BR element. For example: 



       <p nowrap>This paragraph has wordwrap turned off<br>

       and the BR element is used for explicit line breaks

















































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Line Breaks



   Permitted Context: %text

   Content Model: Empty! 



   Line break and tab elements can be used when you need a little more

   control over how the browser renders the text. The <BR> element is

   used to force a line break. 



   For example: 



       This is the first line<br>

       and this is the second<br>

       and this the third



   --Shouldn't we have a conditional line break element like Netscape's

   WBR thats indicates where to break lines when needed and when

   wordwrap is disabled? Rather than an element, shouldn't this be an

   entity - is there one already defined for this purpose?-- 



Permitted Attributes



   ID 

       An SGML identifier used as the target for hypertext links or for

       naming particular elements in associated style sheets.

       Identifiers are NAME tokens and must be unique within the scope

       of the current document. 



   LANG 

       This is one of the ISO standard language abbreviations, e.g.

       "en.uk" for the variation of English spoken in the United

       Kingdom. It can be used by parsers to select language specific

       choices for quotation marks, ligatures and hypenation rules etc.

       The language attribute is composed from the two letter language

       code from ISO 639, optionally followed by a period and a two

       letter country code from ISO 3166. 



   CLASS 

       This a space separated list of SGML NAME tokens and is used to

       subclass tag names. By convention, the class names are

       interpreted hierarchically, with the most general class on the

       left and the most specific on the right, where classes are

       separated by a period. The CLASS attribute is most commonly used

       to attach a different style to some element, but it is

       recommended that where practical class names should be picked on

       the basis of the element's semantics, as this will permit other

       uses, such as restricting search through documents by matching

       on element class names. The conventions for choosing class names

       are outside the scope of this specification. 



   CLEAR 

       When text flows around a figure or table in the margin, you

       sometimes want to start the next line below the figure rather



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       than alongside it. The CLEAR attribute allows you to move down unconditionally:

       

       



       clear=left

           move down until left margin is clear 



       clear=right

           move down until right margin is clear 



       clear=all

           move down until both margins are clear 



       Alternatively, you can decide to place the element alongside the

       figure just so long as there is enough room. The minimum width

       needed is specified as:

       

       



       clear="40 en"

           move down until there is at least 40 en units free 



       clear="100 pixels"

           move down until there is at least 100 pixels free 



       The style sheet (or browser defaults) may provide default

       minimum widths for each class of block-like elements. 























































Dave Raggett                                                           Page 37



HTML 3.0                                                       28th March 1995



Horizontal Tabs



   Permitted Context: %text

   Content Model: Empty! 



   The TAB element can be used when you want fine control over the

   horizontal positioning. The TAB element is used with the <tab

   id=--name--> attribute to define named tab stops. Subsequently, you

   can use the TAB element with the <tab to=--name--> attribute to move

   to the previously defined tab stop. This approach avoids the need to

   know the font metrics in advance. The TAB element, together with

   style sheets, allows conversion software to preserve layout

   information when importing documents created with conventional word

   processing software. 



   For example: 



   <p><b>noct<tab id=t1>ambulant</b> - walking at night<br>

   <tab to=t1>(from Latin: <i>nox noctis</i> night + <i>ambulare</i> walk)



   which is rendered as: 



   noctambulant - walking at night

       (from Latin: --nox noctis-- night + --ambulare-- walk)

   



   The tab stop name (--t1-- in the example) should be unique within

   the current document and composed from an initial letter followed by

   letters, digits or hyphens. 



   Sometimes, you want to make the remainder of the line flush right

   while leaving the earlier words unmoved. This is possible with the

   --align-- attribute. For example: 



   Left part of line<tab align=right>and right part of line.



   which is rendered as: 



   Left part of line                               and right part of line.



Permitted Attributes



   ID 

       An SGML identifier used to name a new tab stop at the current

       position. The scope of the tab stop is the rest of the document. 



   INDENT 

       Specifies the number of en units before the tab stop. The en is

       a typographical unit equal to half the point size. It allows

       authors to control the leading indent before text, e.g. in

       poetry, one might use: <TAB INDENT=6> to indent six en units at

       the start of a line. The INDENT attribute is not meaningful when

       combined with the TO attribute. 



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   TO 

       Specifies a previously defined tab stop (see ID attribute). 



   ALIGN 

       Lines are usually rendered according to the alignment option for

       the enclosing paragraph element. The ALIGN attribute can be used

       to explicitly specify the horizontal alignment:

       

       



       align=left 

           Following text starts immediately after the designated tab

           stop (the default). 



       align=center 

           Following text up to next tab or line break is centered on

           the designated tab stop. If the TO attribute is missing, it

           centers the text between the current left and right margins. 



       align=right 

           Following text up to the next tab or line break is rendered

           flush right to the designated tab stop. If the TO attribute

           is missing, it renders the text flush right against the

           current right margin. 



       align=decimal 

           The following text is searched for the first occurrence of

           the character representing the decimal point. The text up to

           the next tab or line break is then aligned such that the

           decimal point starts at the designated tab stop. If the TO

           attribute is missing, the tab element is treated as a single

           space character. 



   DP 

       This specifies the character to be used for the decimal point

       with the ALIGN attribute, e.g. dp="." (the default) or dp=",".

       The default may be altered by the language context, as set by

       the LANG attribute on enclosing elements. 



   Note: if the specified alignment and tab stop would cause text to

   overlap preceding text, then the tab element may be treated as a

   single space character. 



   --How should the above be rewritten to work with languages which are

   rendered from right to left? What about lines with mixed

   directions?--  















Dave Raggett                                                           Page 39



HTML 3.0                                                       28th March 1995



Hypertext Links



   Permitted Context: %text

   Content Model: %text, but no nested anchors 



   The anchor <A> element is used to define the start and/or

   destination of a hypertext link. In previous versions of HTML it

   provided the only means for defining destination anchors within

   documents, but you can now use any ID attribute as a destination

   anchor so that links can now be made to divisions, paragraphs and

   most other elements. 



   Example: 



   The <A HREF="http://www.w3.org/">World Wide Web Organization</A>

   provides information on Web related standards, mailing lists

   and freeware tools.



   The text between the start and end tag defines the label for the

   link. Selecting the link takes the reader to the document specified

   by the HREF attribute, in this case, the W3O home page. The label

   can include graphics defined with IMG elements. 



   For FIG elements, the anchor element serves a dual role.

   Non-graphical user agents interpret it as a conventional text-based

   hypertext link, while graphical user agents interpret the anchor's

   SHAPE attribute as a graphical hotzone on the figure. 



Permitted Attributes



   ID 

       An SGML identifier used as the target for hypertext links or for

       naming particular elements in associated style sheets.

       Identifiers are NAME tokens and must be unique within the scope

       of the current document. This attribute supercedes the "NAME"

       attribute, see below. 



       For example, the following paragraph is defined as an anchor

       named "potomac": 



       <P ID="potomac">The Potomac river flows into Boston harbour,

       and played an important role in opening up the hinterland

       to early settlers...



       Elsewhere, you can define a link to this paragraph, as follows: 



       <A HREF="#potomac">Boston</A> is a historic city and

       a thriving center of commerce and higher education.



       The reader can select the link labelled "Boston" to see further

       information on the Boston area. 



   LANG 



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       This is one of the ISO standard language abbreviations, e.g.

       "en.uk" for the variation of English spoken in the United

       Kingdom. It can be used by parsers to select language specific

       choices for quotation marks, ligatures and hypenation rules etc.

       The language attribute is composed from the two letter language

       code from ISO 639, optionally followed by a period and a two

       letter country code from ISO 3166. 



   CLASS 

       This a space separated list of SGML NAME tokens and is used to

       subclass tag names. By convention, the class names are

       interpreted hierarchically, with the most general class on the

       left and the most specific on the right, where classes are

       separated by a period. The CLASS attribute is most commonly used

       to attach a different style to some element, but it is

       recommended that where practical class names should be picked on

       the basis of the element's semantics, as this will permit other

       uses, such as restricting search through documents by matching

       on element class names. The conventions for choosing class names

       are outside the scope of this specification. 



   HREF 

       The HREF attribute implies that the anchor acts as the start of

       a hypertext link. The destination is designated by the value of

       the HREF attribute, which is expressed in the Universal Resource

       Identifier (URI) notation. 



   MD 

       Specifies a message digest or cryptographic checksum for the

       linked document designated by the HREF attribute. It is used

       when you want to be sure that a linked object is indeed the same

       one that the author intended, and hasn't been modified in any

       way. For instance, MD="md5:jV2OfH+nnXHU8bnkPAad/mSQlTDZ", which

       specifies an MD5 checksum encoded as a base64 character string.

       The MD attribute is generally allowed for all elements which

       support URI based links. 



   NAME 

       This attribute is used to define a named anchor for use as the

       destination of hypertext links. For example, the following

       defines an anchor than can be used as the destination of a jump

       into a description of the Boston area. 



       The <A NAME="potomac"&gtPotomac river</A> flows into Boston

       harbour.



       Note: the NAME attribute has been superceded by the ID

       attribute. User agents should include support for NAME to ensure

       backwards compatibility with legacy documents produced using

       previous versions of HTML. 



   SHAPE

       This attribute is used within figures to define shaped hotzones



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       for graphical hypertext links. Full details of how to use this

       feature will be given with the description of the figure

       element. The attribute value is a string taking one of the

       following forms:

       

       



       "default" 

           Used to define a default link for the figure background. 



       "circle x, y, r" 

           Where x and y define the center and r specifies the radius. 



       "rect x, y, w, h" 

           Where x, y define the upper left corner and w, h define the

           width and height respectively 



       "polygon x1, y1, x2, y2, ..." 

           Given n pairs of x, y coordinates, the polygon is closed by

           a line linking the n'th point to the first. Intersecting

           polygons use the non-zero winding number rule to determine

           if a point lies inside the polygon. 



       If a pointer event occurs in a region where two or more shapes

       overlap, the distance from the point to the center of gravity of

       each of the overlapping shapes is computed and the closest one

       chosen. This feature is useful when you want lots of closely

       spaced hotzones, for example over points on a map, as it allows

       you to use simple shapes without worrying about overlaps. 



       Note: The x coordinate increases to the right, and the y

       coordinate increases downwards in the same way as IMG and image

       maps. If both numbers are integers, the coordinates are

       interpreted as pixel offsets from the upper left corner of the

       figure. Otherwise, the coordinates are interpreted as scaled

       values in the range 0.0 to 1.0 across the figure. Note the

       syntax is tolerant of repeated white space characters between

       tokens. 



   TITLE 

       This is informational only and describes the object specified

       with the HREF attribute. It can be used for object types that

       don't possess titles, such as graphics, plain text and Gopher

       menus. 



   REL 

       Used to describe the relationship of the linked object specified

       with the HREF attribute. The set of relationship names is not

       part of this specification, although "Path" and "Node" are

       reserved for future use with hypertext paths or guided tours.

       The REL attribute can be used to support search for links

       serving particular relationships. 





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   REV 

       This defines a reverse relationship. A link from document A to

       document B with REV=--relation-- expresses the same relationship

       as a link from B to A with REL=--relation--. REV=made is

       sometimes used to identify the document author, either the

       author's email address with a --mailto-- URI, or a link to the

       author's home page. Tables of contents can use anchors with

       REV="ToC" to allow software to insert page numbers when printing

       hypertext documents. The plain text version of this

       specification was generated in this way! 

























































































Dave Raggett                                                           Page 43



HTML 3.0                                                       28th March 1995



Overview of Character-Level Elements



   Permitted Context: %text

   Content Model: %text 



   Character level elements are used to specify either the structural

   meaning or the physical appearence of marked text without causing a

   paragraph break. Like most other elements, character level elements

   include both start and end tags. Only the characters between the

   tags are effected. For example: 



       This is <EM>emphasized</EM> text.



   Highlighting elements are allowed within the content of other

   highlighting elements, but implementations are not required to

   render these nested highlighting elements distinctly from non-nested

   elements. For example, implementations may render the following two

   cases identically: 



       plain <B>bold <I>italic</I></B>



       plain <B>bold </B><I>italic</I>



   Some character highlighting styles are more explicit than others

   about how they should be physically represented. Designate the

   information type rather than the character format wherever possible,

   unless for example, it is necessary to refer to the text as in "The

   italic parts are mandatory". 



Permitted Attributes



   ID 

       An SGML identifier used as the target for hypertext links or for

       naming particular elements in associated style sheets.

       Identifiers are NAME tokens and must be unique within the scope

       of the current document. 



   LANG 

       This is one of the ISO standard language abbreviations, e.g.

       "en.uk" for the variation of English spoken in the United

       Kingdom. It can be used by parsers to select language specific

       choices for quotation marks, ligatures and hypenation rules etc.

       The language attribute is composed from the two letter language

       code from ISO 639, optionally followed by a period and a two

       letter country code from ISO 3166. 



   CLASS 

       This a space separated list of SGML NAME tokens and is used to

       subclass tag names. By convention, the class names are

       interpreted hierarchically, with the most general class on the

       left and the most specific on the right, where classes are

       separated by a period. The CLASS attribute is most commonly used

       to attach a different style to some element, but it is



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       recommended that where practical class names should be picked on

       the basis of the element's semantics, as this will permit other

       uses, such as restricting search through documents by matching

       on element class names. The conventions for choosing class names

       are outside the scope of this specification. 



































































































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Information Type Elements



   EM 

       The <EM> element provides typographic emphasis, typically

       italics. While <EM> and <I> often give the same effect, use <EM>

       except where it is necessary in the text to refer to the

       formatting, as in "The italic parts are mandatory". This will

       help to ensure consistency between documents from various

       sources if (for example) the reader prefers to use color in

       place of italics for emphasis. 



   CITE 

       The <CITE> element specifies a citation. Sections tagged with

       the CITE element are typically rendered in italics. 



   STRONG 

       The <STRONG> element provides strong typographic emphasis,

       typically bold. 



   CODE 

       The <CODE> element indicates an example of code; typically

       rendered in a mono-spaced font. Do not confuse with PRE. 



   SAMP 

       The <SAMP> element indicates a sequence of literal characters. 



   KBD 

       The <KBD> element indicates text typed (keyboarded) by the user.

       It might typically be used in an instruction manual. 



   VAR 

       The <VAR> element indicates a variable name, and might typically

       be used in an instruction manual. 



   DFN 

       The <DFN> element indicates the defining instance of a term.

       --New in 3.0--. 



   Q 

       The <Q> element is used for a short quotation. It is typically

       shown enclosed in quotation marks as appropriate to the language

       context. For English these would be matching double or single

       quotation marks, alternating for nested quotes. The language

       context is set by the LANG attribute. --New in 3.0--. 



   LANG 

       The <LANG> element is used to alter the language context when it

       is inappropriate to do this with other character-level elements.

       --New in 3.0--. 



   AU 

       The <AU> element indicates the name of an author. --New in

       3.0--. 



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HTML 3.0                                                       28th March 1995





   PERSON 

       The <PERSON> element is used for names of people to allow these

       to be extracted automatically by indexing programs. --New in

       3.0--. 



   ACRONYM 

       The <ACRONYM> element is used to markup acronyms. --New in

       3.0--. 



   ABBREV 

       The <ABBREV> element is used to markup abbreviations. --New in

       3.0--. 



   INS 

       The <INS> element is used for inserted text, for instance in

       legal documents. --New in 3.0--. 



   DEL 

       The <DEL> is used for deleted text, for instance in legal

       documents. --New in 3.0--. 



   An example: 



   This text contains an <em>emphasized</em> word.

   <strong>Don't assume</strong> that it will be italic!

   It was made with the <code>EM</code> element. A cite is

   often italic and has no formally required structure:

   <cite>Moby Dick</cite> is a book title.



















































Dave Raggett                                                           Page 47



HTML 3.0                                                       28th March 1995



Font Style Elements



   These elements may be nested within one another. Browsers should,

   where practical, aim to combine different types of highlighting as

   required. 



   B (Boldface) 

       The <B> element specifies that the enclosed text should be

       displayed in a boldface. If this is not practical, an

       alternative mapping is allowed. 



   I (Italic) 

       The <I> element specifies that the enclosed text should be

       displayed, if practical, in an italic font (or slanted). 



   TT (TeleType) 

       The <TT> element specifies that the enclosed text should be

       displayed, if practical, in a fixed-pitch typewriter font. 



   U (Underline) 

       The <U> element specifies that the enclosed text should be

       displayed, if practical, as underlined. --Not widely supported-- 



   S (Strike through) 

       The <S> element specifies that the enclosed text should be

       displayed with a horizontal line striking through the text. If

       this is not practical, an alternative mapping is allowed. --New

       in 3.0--. 



   BIG (Big print) 

       The <BIG> element specifies that the enclosed text should be

       displayed, if practical, using a big font (compared with the

       current font). --New in 3.0--. 



   SMALL (Small print) 

       The <SMALL> element specifies that the enclosed text should be

       displayed, if practical, using a small font (compared with

       normal text). --New in 3.0--. 



   SUB (Subscript) 

       The <SUB> element specifies that the enclosed text should be

       displayed as a subscript, and if practical, using a smaller font

       (compared with normal text). The ALIGN attribute for SUB is only

       meaningful within the MATH element. --New in 3.0--. 



   SUP (Superscript) 

       The <SUP> element specifies that the enclosed text should be

       displayed as a superscript, and if practical, using a smaller

       font (compared with normal text). The ALIGN attribute for SUP is

       only applicable within the MATH element. --New in 3.0--. 



   An example: 





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HTML 3.0                                                       28th March 1995



   This text contains some <b><i>bold italic</i></b> text, some

   <S>struck through</S> text and some <SMALL>small print</SMALL>.









































































































Dave Raggett                                                           Page 49



HTML 3.0                                                       28th March 1995



The IMG (Image) Element



   Permitted Context: %text

   Content Model: Empty! 



   The <IMG> tag is used to incorporate in-line graphics (typically

   icons or small graphics) into an HTML document. This element is NOT

   intended for embedding other HTML text. For large figures with

   captions and text flow see FIG element. 



   Example: 



   <IMG SRC="tajmahal.gif" ALT="The Taj Mahal">



   Browsers that cannot display in-line images ignore the IMG element

   unless it contains the ALT attribute. Note that some browsers can

   display (or print) linked graphics but not in-line graphics. If the

   graphic is essential, you may want to create a link to it rather

   than to put it in-line. If the graphic is essentially decorative,

   then IMG is appropriate. 



Permitted Attributes



   ID 

       An SGML identifier used as the target for hypertext links or for

       naming particular elements in associated style sheets.

       Identifiers are NAME tokens and must be unique within the scope

       of the current document. 



   LANG 

       This is one of the ISO standard language abbreviations, e.g.

       "en.uk" for the variation of English spoken in the United

       Kingdom. It can be used by parsers to select language specific

       choices for quotation marks, ligatures and hypenation rules etc.

       The language attribute is composed from the two letter language

       code from ISO 639, optionally followed by a period and a two

       letter country code from ISO 3166. 



   CLASS 

       This a space separated list of SGML NAME tokens and is used to

       subclass tag names. By convention, the class names are

       interpreted hierarchically, with the most general class on the

       left and the most specific on the right, where classes are

       separated by a period. The CLASS attribute is most commonly used

       to attach a different style to some element, but it is

       recommended that where practical class names should be picked on

       the basis of the element's semantics, as this will permit other

       uses, such as restricting search through documents by matching

       on element class names. The conventions for choosing class names

       are outside the scope of this specification. 



   SRC (Source) 

       The SRC attribute specifies the URI for the image to be



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HTML 3.0                                                       28th March 1995



       embedded. Its syntax is the same as that of the HREF attribute

       of the <A> tag. SRC is mandatory. 



   MD 

       Specifies a message digest or cryptographic checksum for the

       associated graphic specified by the SRC attribute. It is used

       when you want to be sure that the image is indeed the same one

       that the author intended, and hasn't been modified in any way.

       For instance, MD="md5:jV2OfH+nnXHU8bnkPAad/mSQlTDZ", which

       specifies an MD5 checksum encoded as a base64 character string.

       The MD attribute is generally allowed for all elements which

       support URI based links. 



   WIDTH 

       Optional suggested width for the image. By default, this is

       given in pixels. 



   HEIGHT 

       Optional suggested height for the image. By default, this is

       given in pixels. 



   UNITS 

       This optional attribute specifies the units for the width and

       height attributes. It is one of: units=pixels (the default) or

       units=en (half the point size). 



   ALIGN 

       Take values TOP or MIDDLE or BOTTOM, defining whether the top or

       middle or bottom of the graphic should be aligned with the

       baseline for the text line in which the IMG element appears. 



       With ALIGN=LEFT, the graphic will float down and over to the

       current left margin, and subsequent text will wrap around the

       right hand side of the graphic. Likewise for ALIGN=RIGHT, the

       graphic aligns with the current right margin and, and text wraps

       around the left. It is inappropriate to use this feature for

       larger graphics as these are best represented with the FIG

       element. 



   ALT (Alternate text) 

       Optional alternative text as an alternative to the graphics for

       display in text-only environments. The alt text can contain

       entities e.g. for accented characters or special symbols, but it

       can't contain markup. The latter is possible, however, with the

       FIG element. 



   ISMAP 

       An image map is a graphical map by which users can navigate

       transparently from one information resource to another. The

       ISMAP attribute identifies an image as an image map. The IMG

       element can then be used as part of the label for a hypertext

       link (see the anchor element). When the user clicks on the image

       the location clicked is sent to the server designated by the



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       hypertext link. 



       For example: 



       <A HREF="http://machine/htbin/imagemap/sample">

       <IMG SRC="sample.gif" ISMAP></A>



   Note: There are drawbacks from having the server process clicks on

   images: the delay in getting feedback and the inability to change

   the pointer cursor on the fly as it moves over hotzones. Client-side

   processing of events is possible if one of the following applies: 



   *   The server may allow the image map to be downloaded and

       processed locally. This should work with legacy documents

       produced using earlier versions of HTML. 



   *   Using an image format that includes image hotzones as part of

       the file format. 



   *   The FIG element provides for client-side image maps as a unified

       part of the figure description. It offers a number of advantages

       over IMG, including captions, markup in alt text and text flow

       around figures. 































































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UL (Unordered List)



   Permitted Context: %Body.Content, %flow, %block

   Content Model: Optional list header (LH), followed by one or more

   list items(LI) 



   An unordered list typically is a bulleted list of items. HTML 3.0

   gives you the ability to customise the bullets, to do without

   bullets and to wrap list items horizontally or vertically for

   multicolumn lists. 



   The opening list tag must be <UL>. It is followed by an optional

   list header (<LH>caption</LH>) and then by the first list item

   (<LI>). For example: 



       <UL>

         <LH>Table Fruit</LH>

         <LI>apples

         <LI>oranges

         <LI>bananas

       </UL>



   which could be rendered as: 



Table Fruit



   *   apples 



   *   oranges 



   *   bananas 



   Note: Some legacy documents may include headers or plain text before

   the first LI element. Implementors of HTML 3.0 user agents are

   advised to cater for this possibility in order to handle badly

   formed legacy documents. 



MENU and DIR elements



   These elements are superceded by extensions to the UL element. User

   agents are advised to continue to support them for the sake of

   legacy documents. Both MENU and DIR consist of one or more LI

   elements, similar to UL. MENU lists are typically rendered without

   bullets in a more compact style than UL. You can get the same effect

   with <UL PLAIN>. DIR lists are used to present lists of items

   containing up to 20 characters each. Items in a DIR list are

   arranged in columns. You can get the same effect with <UL PLAIN

   WRAP=HORIZ>. 



Permitted Attributes for the UL Element



   ID 

       An SGML identifier used as the target for hypertext links or for



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HTML 3.0                                                       28th March 1995



       naming particular elements in associated style sheets.

       Identifiers are NAME tokens and must be unique within the scope

       of the current document. 



   LANG 

       This is one of the ISO standard language abbreviations, e.g.

       "en.uk" for the variation of English spoken in the United

       Kingdom. It can be used by parsers to select language specific

       choices for quotation marks, ligatures and hypenation rules etc.

       The language attribute is composed from the two letter language

       code from ISO 639, optionally followed by a period and a two

       letter country code from ISO 3166. 



   CLASS 

       This a space separated list of SGML NAME tokens and is used to

       subclass tag names. By convention, the class names are

       interpreted hierarchically, with the most general class on the

       left and the most specific on the right, where classes are

       separated by a period. The CLASS attribute is most commonly used

       to attach a different style to some element, but it is

       recommended that where practical class names should be picked on

       the basis of the element's semantics, as this will permit other

       uses, such as restricting search through documents by matching

       on element class names. The conventions for choosing class names

       are outside the scope of this specification. 



   CLEAR 

       This attribute is common to all block-like elements. When text

       flows around a figure or table in the margin, you sometimes want

       to start an element like a header, paragraph or list below the

       figure rather than alongside it. The CLEAR attribute allows you

       to move down unconditionally:

       

       



       clear=left

           move down until left margin is clear 



       clear=right

           move down until right margin is clear 



       clear=all

           move down until both margins are clear 



       Alternatively, you can decide to place the element alongside the

       figure just so long as there is enough room. The minimum width

       needed is specified as:

       

       



       clear="40 en"

           move down until there is at least 40 en units free 





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HTML 3.0                                                       28th March 1995



       clear="100 pixels"

           move down until there is at least 100 pixels free 



       The style sheet (or browser defaults) may provide default

       minimum widths for each class of block-like elements. 



   PLAIN 

       The presence of this attribute suppresses the display of

       bullets, e.g. <UL PLAIN>. 



   SRC 

       Specifies an image for use as a bullet. The image is specified

       as a URI. This attribute may appear together with the MD

       attribute. 



   MD 

       Specifies a message digest or cryptographic checksum for the

       associated graphic specified by the SRC attribute. It is used

       when you want to be sure that a linked object is indeed the same

       one that the author intended, and hasn't been modified in any

       way. For instance, MD="md5:jV2OfH+nnXHU8bnkPAad/mSQlTDZ", which

       specifies an MD5 checksum encoded as a base64 character string.

       The MD attribute is generally allowed for all elements which

       support URI based links. 



   DINGBAT 

       Specifies an iconic image for use as a bullet. The icon is

       specified as an entity name. A list of standard icon entity

       names for HTML 3.0 is given in an appendix of this

       specification, e.g. folder is the entity name for an icon

       denoting a directory or folder. 



   WRAP 

       The WRAP attribute is used for multicolumn lists. Use wrap=vert

       if you want to arrange the list items down the page before

       wrapping to the next column. Use wrap=horiz if you want to

       arrange the items across the page (less useful). The user agent

       is responsible for determining how many columns are appropriate. 



   COMPACT 

       The presence of this attribute indicates the user agent should

       use reduced interitem spacing. In practice, there are several

       ways to increase the compactness of lists: reduced vertical

       interitem spacing, smaller font size, or even to avoid line

       breaks between items. This is best handled through associated

       style sheets and the class attribute. 

















Dave Raggett                                                           Page 55



HTML 3.0                                                       28th March 1995



LH (List Header)



   Permitted Context: Immediately following UL, OL or DL

   Content Model: %text 



   The LH or list header element is used to provide a title for a list.

   User agents can use this in place of the full list when a mechanism

   is provided to fold and unfold nested lists. 



Permitted Attributes for the LH Element



   ID 

       An SGML identifier used as the target for hypertext links or for

       naming particular elements in associated style sheets.

       Identifiers are NAME tokens and must be unique within the scope

       of the current document. 



   LANG 

       This is one of the ISO standard language abbreviations, e.g.

       "en.uk" for the variation of English spoken in the United

       Kingdom. It can be used by parsers to select language specific

       choices for quotation marks, ligatures and hypenation rules etc.

       The language attribute is composed from the two letter language

       code from ISO 639, optionally followed by a period and a two

       letter country code from ISO 3166. 



   CLASS 

       This a space separated list of SGML NAME tokens and is used to

       subclass tag names. By convention, the class names are

       interpreted hierarchically, with the most general class on the

       left and the most specific on the right, where classes are

       separated by a period. The CLASS attribute is most commonly used

       to attach a different style to some element, but it is

       recommended that where practical class names should be picked on

       the basis of the element's semantics, as this will permit other

       uses, such as restricting search through documents by matching

       on element class names. The conventions for choosing class names

       are outside the scope of this specification. 

































Dave Raggett                                                           Page 56



HTML 3.0                                                       28th March 1995



LI (List Item)



   Permitted Context: UL or OL

   Content Model: %flow 



   The LI or list item element is used for items in both ordered and

   unordered lists. 



   Note: The content model for list items is quite broad, including

   paragraphs, lists, performatted text, forms, tables, figures and

   admonishments. Headers are not permitted, although implementors of

   HTML 3.0 user agents are advised to cater for this possibility in

   order to handle badly formed legacy documents. If %html.recommended

   is active, the HTML 3.0 DTD expects you to enclose plain text in a

   block element such as <P> 



Permitted Attributes for the LI Element



   ID 

       An SGML identifier used as the target for hypertext links or for

       naming particular elements in associated style sheets.

       Identifiers are NAME tokens and must be unique within the scope

       of the current document. 



   LANG 

       This is one of the ISO standard language abbreviations, e.g.

       "en.uk" for the variation of English spoken in the United

       Kingdom. It can be used by parsers to select language specific

       choices for quotation marks, ligatures and hypenation rules etc.

       The language attribute is composed from the two letter language

       code from ISO 639, optionally followed by a period and a two

       letter country code from ISO 3166. 



   CLASS 

       This a space separated list of SGML NAME tokens and is used to

       subclass tag names. By convention, the class names are

       interpreted hierarchically, with the most general class on the

       left and the most specific on the right, where classes are

       separated by a period. The CLASS attribute is most commonly used

       to attach a different style to some element, but it is

       recommended that where practical class names should be picked on

       the basis of the element's semantics, as this will permit other

       uses, such as restricting search through documents by matching

       on element class names. The conventions for choosing class names

       are outside the scope of this specification. 



   CLEAR 

       This attribute is common to all block-like elements. When text

       flows around a figure or table in the margin, you sometimes want

       to start the list item below the figure rather than alongside

       it. The CLEAR attribute allows you to move down unconditionally:

       

       



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HTML 3.0                                                       28th March 1995





       clear=left

           move down until left margin is clear 



       clear=right

           move down until right margin is clear 



       clear=all

           move down until both margins are clear 



       Alternatively, you can decide to place the element alongside the

       figure just so long as there is enough room. The minimum width

       needed is specified as:

       

       



       clear="40 en"

           move down until there is at least 40 en units free 



       clear="100 pixels"

           move down until there is at least 100 pixels free 



       The style sheet (or browser defaults) may provide default

       minimum widths for each class of block-like elements. 



   SRC 

       Specifies an image for use as a bullet. The image is specified

       as a URI. This attribute may appear together with the MD

       attribute. 



   MD 

       Specifies a message digest or cryptographic checksum for the

       associated graphic specified by the SRC attribute. It is used

       when you want to be sure that a linked object is indeed the same

       one that the author intended, and hasn't been modified in any

       way. For instance, MD="md5:jV2OfH+nnXHU8bnkPAad/mSQlTDZ", which

       specifies an MD5 checksum encoded as a base64 character string.

       The MD attribute is generally allowed for all elements which

       support URI based links. 



   DINGBAT 

       Specifies an iconic image for use as a bullet. The icon is

       specified as an entity name. A list of standard icon entity

       names for HTML 3.0 is given in an appendix of this

       specification, e.g. folder is the entity name for an icon

       denoting a directory or folder. 



   SKIP 

       Increments the sequence number before rendering the element. It

       is used when headers have been left out of the sequence. For

       instance, SKIP=3 advances the sequence number past 3 omitted

       items. 





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HTML 3.0                                                       28th March 1995



OL (Ordered List)



   Permitted Context: %Body.Content, %flow, %block

   Content Model: Optional list header (LH), followed by one or more

   list items(LI) 



   An ordered list typically is a numbered list of items. HTML 3.0

   gives you the ability to control the sequence number - to continue

   where the previous list left off, or to start at a particular

   number. The numbering style is left to associated style sheets, e.g.

   whether nested lists contribute to a compound item number, e.g.

   "3.1.5", or whether numbers are rendered as arabic, upper or lower

   case roman numerals or using the numbering scheme appropriate to the

   language context. 



   The opening list tag must be <OL>. It is followed by an optional

   list header (<LH>caption</LH>) and then by the first list item

   (<LI>). For example: 



       <OL>

         <LH>Meeting Agenda</LH>

         <LI>Minutes of the last meeting

         <LI>Do we need yet more meetings?

         <LI>Any other business

       </OL>



   which could be rendered as: 



Meeting Agenda



   1.  Minutes of the last meeting 



   2.  Do we need yet more meetings? 



   3.  Any other business 



   Note: Some legacy documents may include headers or plain text before

   the first LI element. Implementors of HTML 3.0 user agents are

   advised to cater for this possibility in order to handle badly

   formed legacy documents. 



Permitted Attributes for the OL Element



   ID 

       An SGML identifier used as the target for hypertext links or for

       naming particular elements in associated style sheets.

       Identifiers are NAME tokens and must be unique within the scope

       of the current document. 



   LANG 

       This is one of the ISO standard language abbreviations, e.g.

       "en.uk" for the variation of English spoken in the United

       Kingdom. It can be used by parsers to select language specific



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HTML 3.0                                                       28th March 1995



       choices for quotation marks, ligatures and hypenation rules etc.

       The language attribute is composed from the two letter language

       code from ISO 639, optionally followed by a period and a two

       letter country code from ISO 3166. 



   CLASS 

       This a space separated list of SGML NAME tokens and is used to

       subclass tag names. By convention, the class names are

       interpreted hierarchically, with the most general class on the

       left and the most specific on the right, where classes are

       separated by a period. The CLASS attribute is most commonly used

       to attach a different style to some element, but it is

       recommended that where practical class names should be picked on

       the basis of the element's semantics, as this will permit other

       uses, such as restricting search through documents by matching

       on element class names. The conventions for choosing class names

       are outside the scope of this specification. 



   CLEAR 

       This attribute is common to all block-like elements. When text

       flows around a figure or table in the margin, you sometimes want

       to start an element like a header, paragraph or list below the

       figure rather than alongside it. The CLEAR attribute allows you

       to move down unconditionally:

       

       



       clear=left

           move down until left margin is clear 



       clear=right

           move down until right margin is clear 



       clear=all

           move down until both margins are clear 



       Alternatively, you can decide to place the element alongside the

       figure just so long as there is enough room. The minimum width

       needed is specified as:

       

       



       clear="40 en"

           move down until there is at least 40 en units free 



       clear="100 pixels"

           move down until there is at least 100 pixels free 



       The style sheet (or browser defaults) may provide default

       minimum widths for each class of block-like elements. 



   CONTINUE 

       Don't restart the sequence number, i.e. continue where previous



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HTML 3.0                                                       28th March 1995



       list left off, e.g. <OL CONTINUE> 



   SEQNUM 

       Set the starting sequence number for the first item, e.g. <OL

       SEQNUM=23> 



   COMPACT 

       The presence of this attribute indicates the user agent should

       use reduced interitem spacing. In practice, there are several

       ways to increase the compactness of lists: reduced vertical

       interitem spacing, smaller font size, or even to avoid line

       breaks between items. This is best handled through associated

       style sheets and the class attribute. 



















































































Dave Raggett                                                           Page 61



HTML 3.0                                                       28th March 1995



DL - Definition Lists



   Permitted Context: %Body.Content, %flow, %block

   Content Model: Optional list header(LH), followed by one or more

   terms(DT) and definitions(DD). 



   A definition list is a list of terms and corresponding definitions.

   Definition lists are typically formatted with the term on the left

   with the definition following on the right or on the next line. The

   definition text is typically indented with respect to the term. 



   An alternative format places the term left aligned in a wide margin

   and the definition on one or more lines to the right of the term. If

   the DT term does not fit in the DT column (one third of the display

   area), it may be extended across the page with the DD section moved

   to the next line, or it may be wrapped onto successive lines of the

   left hand column. 



   The opening list tag must be <DL>. It is followed by an optional

   list header (<LH>caption</LH>) and then by term names (<DT>) and

   definitions (<DD>). For example: 



   <DL>

   <LH>List Header</LH>

   <DT>Term 1<dd>This is the definition of the first term.

   <DT>Term 2<dd>This is the definition of the second term.

   </DL>



   which could be rendered as: 



List Header



   Term 1

       This is the definition of the first term. 



   Term 2

       This is the definition of the second term. 



   The definition list element can take the COMPACT attribute, which

   suggests that a compact rendering be used, and is appropriate if the

   list elements are small and/or the entire list is large. 



   Note: Use the NOTE element when you want to have an indented note.

   The practice of using <DD> elements without corresponding <DT>

   elements is deprecated. 



Permitted Attributes for the DL Element



   ID 

       An SGML identifier used as the target for hypertext links or for

       naming particular elements in associated style sheets.

       Identifiers are NAME tokens and must be unique within the scope

       of the current document. 



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   LANG 

       This is one of the ISO standard language abbreviations, e.g.

       "en.uk" for the variation of English spoken in the United

       Kingdom. It can be used by parsers to select language specific

       choices for quotation marks, ligatures and hypenation rules etc.

       The language attribute is composed from the two letter language

       code from ISO 639, optionally followed by a period and a two

       letter country code from ISO 3166. 



   CLASS 

       This a space separated list of SGML NAME tokens and is used to

       subclass tag names. By convention, the class names are

       interpreted hierarchically, with the most general class on the

       left and the most specific on the right, where classes are

       separated by a period. The CLASS attribute is most commonly used

       to attach a different style to some element, but it is

       recommended that where practical class names should be picked on

       the basis of the element's semantics, as this will permit other

       uses, such as restricting search through documents by matching

       on element class names. The conventions for choosing class names

       are outside the scope of this specification. 



   CLEAR 

       This attribute is common to all block-like elements. When text

       flows around a figure or table in the margin, you sometimes want

       to start an element like a header, paragraph or list below the

       figure rather than alongside it. The CLEAR attribute allows you

       to move down unconditionally:

       

       



       clear=left

           move down until left margin is clear 



       clear=right

           move down until right margin is clear 



       clear=all

           move down until both margins are clear 



       Alternatively, you can decide to place the element alongside the

       figure just so long as there is enough room. The minimum width

       needed is specified as:

       

       



       clear="40 en"

           move down until there is at least 40 en units free 



       clear="100 pixels"

           move down until there is at least 100 pixels free 





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HTML 3.0                                                       28th March 1995



       The style sheet (or browser defaults) may provide default

       minimum widths for each class of block-like elements. 



   COMPACT 

       The presence of this attribute indicates the user agent should

       use reduced interitem spacing. The COMPACT attribute may also

       reduce the width of the left-hand (DT) column. 



       In practice, there are several ways to increase the compactness

       of lists: reduced vertical interitem spacing, smaller font size,

       or even to avoid line breaks between items. This is best handled

       through associated style sheets and the class attribute. 



       The opening list tag must be DL COMPACT. It must be immediately

       followed by the first term (DT). For example: 



       <DL compact>

       <DT>Term<DD>This is the first definition in compact format.

       <DT>Term<DD>This is the second definition in compact format.

       </DL>





































































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HTML 3.0                                                       28th March 1995



DT - Term Name



   Permitted Context: DL

   Content Model: %text 



   The DT tag element specifies a term name, and you can have several

   terms per DD element. 



   Note: Term names are restricted to character level markup only,

   including epmhasis, inline images and footnotes. Paragraph tags and

   other block-like element such as headers are not permitted, although

   implementors of HTML 3.0 user agents are advised to cater for this

   possibility in order to handle badly formed legacy documents. 



Permitted Attributes for the DT Element



   ID 

       An SGML identifier used as the target for hypertext links or for

       naming particular elements in associated style sheets.

       Identifiers are NAME tokens and must be unique within the scope

       of the current document. 



   LANG 

       This is one of the ISO standard language abbreviations, e.g.

       "en.uk" for the variation of English spoken in the United

       Kingdom. It can be used by parsers to select language specific

       choices for quotation marks, ligatures and hypenation rules etc.

       The language attribute is composed from the two letter language

       code from ISO 639, optionally followed by a period and a two

       letter country code from ISO 3166. 



   CLASS 

       This a space separated list of SGML NAME tokens and is used to

       subclass tag names. By convention, the class names are

       interpreted hierarchically, with the most general class on the

       left and the most specific on the right, where classes are

       separated by a period. The CLASS attribute is most commonly used

       to attach a different style to some element, but it is

       recommended that where practical class names should be picked on

       the basis of the element's semantics, as this will permit other

       uses, such as restricting search through documents by matching

       on element class names. The conventions for choosing class names

       are outside the scope of this specification. 



   CLEAR 

       When text flows around a figure or table in the margin, you

       sometimes want to start the term name below the figure rather

       than alongside it. The CLEAR attribute allows you to move down unconditionally:

       

       



       clear=left

           move down until left margin is clear 



Dave Raggett                                                           Page 65



HTML 3.0                                                       28th March 1995





       clear=right

           move down until right margin is clear 



       clear=all

           move down until both margins are clear 



       Alternatively, you can decide to place the element alongside the

       figure just so long as there is enough room. The minimum width

       needed is specified as:

       

       



       clear="40 en"

           move down until there is at least 40 en units free 



       clear="100 pixels"

           move down until there is at least 100 pixels free 



       The style sheet (or browser defaults) may provide default

       minimum widths for each class of block-like elements. 



































































Dave Raggett                                                           Page 66



HTML 3.0                                                       28th March 1995



DD - Term Definition



   Permitted Context: DL

   Content Model: %flow 



   The DD tag element specifies a term definition, and follows one or

   more DT elements. 



   Note: The content model for term definitions is quite broad,

   including paragraphs, lists, performatted text, forms, tables,

   figures and admonishments. Headers are not permitted, although

   implementors of HTML 3.0 user agents are advised to cater for this

   possibility in order to handle badly formed legacy documents. If

   %html.recommended is active, the HTML 3.0 DTD expects you to enclose

   plain text in a block element such as <P> 



Permitted Attributes for the DD Element



   ID 

       An SGML identifier used as the target for hypertext links or for

       naming particular elements in associated style sheets.

       Identifiers are NAME tokens and must be unique within the scope

       of the current document. 



   LANG 

       This is one of the ISO standard language abbreviations, e.g.

       "en.uk" for the variation of English spoken in the United

       Kingdom. It can be used by parsers to select language specific

       choices for quotation marks, ligatures and hypenation rules etc.

       The language attribute is composed from the two letter language

       code from ISO 639, optionally followed by a period and a two

       letter country code from ISO 3166. 



   CLASS 

       This a space separated list of SGML NAME tokens and is used to

       subclass tag names. By convention, the class names are

       interpreted hierarchically, with the most general class on the

       left and the most specific on the right, where classes are

       separated by a period. The CLASS attribute is most commonly used

       to attach a different style to some element, but it is

       recommended that where practical class names should be picked on

       the basis of the element's semantics, as this will permit other

       uses, such as restricting search through documents by matching

       on element class names. The conventions for choosing class names

       are outside the scope of this specification. 



   CLEAR 

       When text flows around a figure or table in the margin, you

       sometimes want to start term definition below the figure rather

       than alongside it. The CLEAR attribute allows you to move down unconditionally:

       

       





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HTML 3.0                                                       28th March 1995



       clear=left

           move down until left margin is clear 



       clear=right

           move down until right margin is clear 



       clear=all

           move down until both margins are clear 



       Alternatively, you can decide to place the element alongside the

       figure just so long as there is enough room. The minimum width

       needed is specified as:

       

       



       clear="40 en"

           move down until there is at least 40 en units free 



       clear="100 pixels"

           move down until there is at least 100 pixels free 



       The style sheet (or browser defaults) may provide default

       minimum widths for each class of block-like elements. 































































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Figures



   Permitted Context: %body.content, %flow, %block

   Content Model: Optional OVERLAYs followed by an optional CAPTION,

   then %body.content and finally an optional CREDIT 



   The FIG element is used for figures. Subsequent elements will be

   flowed around the figure if there is sufficient room. This behaviour

   is disabled when the align attribute is --center-- (the default) or

   --justify--. 



   Figure overlays provide for more effective use of caching as small

   changes to a figure in a subsequent document incur only the penalty

   of downloading the overlays and not the larger base figure, as the

   latter is already in the cache. 



   The figure description text is intended to convey the content of the

   figure for people with non-graphical user agents, while the figure

   caption and credit are rendered on both graphical and non-graphical

   user agents. The FIG element improves on the IMG element by allowing

   authors to use markup for the description text. The content model

   allows authors to include headers, which is appropriate when the

   headers are part of the image data. It also allows graphical

   hypertext links to be specified in the markup and interpreted by the

   user agent rather than the server. 



   The anchor elements in the figure description text play a dual role:

   Non-graphical user agents show conventional hypertext links, while

   for graphical user agents, the same anchor elements specify

   graphical hypertext links, with the SHAPE attribute designating the

   hotzones. This is designed to simplify the task of authors writing

   for both audiences. Hopefully, the FIG element will help to combat

   the tendency for authors to forget about people limited to terminal

   access or the visually impaired relying on text to speech, as the

   new element forces you to write description text to define the

   graphical hypertext links. 



   For some applications the hotzones are dynamically defined by

   programs running on the server. HTML 3.0 allows clicks and drags to

   be passed to the server with the IMAGEMAP attribute. Hotzones may

   also be specified as part of the graphics data format e.g. as in

   VRML. Hotzones in the FIG element take precedence over hotzones in

   the graphics data, which in turn take precedence over passing events

   to a server imagemap program. 



   Hotzones in overlay graphics data take precedence over hotzones in

   figure data. Similarly, the imagemap attribute in overlays takes

   precedence over the imagemap attribute for the figure. For a group

   of overlapping overlays the precedence is determined by the order

   the OVERLAY elements appear within the FIG element. Later overlays

   take precedence over earlier ones. 



Examples



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   Photographic image with caption and credits: 



   <FIG SRC="nicodamus.jpeg">

     <CAPTION>Ground dweller: <I>Nicodamus bicolor</I>

     builds silk snares</CAPTION>

     <P>A small hairy spider light fleshy red in color with a brown abdomen.

     <CREDIT>J. A. L. Cooke/OSF</CREDIT>

   </FIG>



   Company home page: 



   <FIG SRC="mainmenu.gif">

    <H1>Access HP from Hewlett Packard</H1>

    <P>Select between:

    <UL>

     <LI><A HREF="guide.html" SHAPE="rect 30,200,60,16">Access Guide</A>

     <LI><A HREF="about.html" SHAPE="rect 100,200,50,16">About HP</A>

     <LI><A HREF="guide.html" SHAPE="rect 160,200,30,16">News</A>

     <LI><A HREF="guide.html" SHAPE="rect 200,200,50,16">Products</A>

     <LI><A HREF="guide.html" SHAPE="rect 260,200,80,16">Worldwide Contacts</A>

    </UL>

   </FIG>



   Aerial photograph with map overlay: 



   <FIG SRC="newyork.jpeg">

     <OVERLAY SRC="map.gif">

     <P>New York from the air!

   </FIG>



Permitted Attributes



   ID 

       An SGML identifier used as the target for hypertext links or for

       naming particular elements in associated style sheets.

       Identifiers are NAME tokens and must be unique within the scope

       of the current document. 



   LANG 

       This is one of the ISO standard language abbreviations, e.g.

       "en.uk" for the variation of English spoken in the United

       Kingdom. It can be used by parsers to select language specific

       choices for quotation marks, ligatures and hypenation rules etc.

       The language attribute is composed from the two letter language

       code from ISO 639, optionally followed by a period and a two

       letter country code from ISO 3166. 



   CLASS 

       This a space separated list of SGML NAME tokens and is used to

       subclass tag names. By convention, the class names are

       interpreted hierarchically, with the most general class on the

       left and the most specific on the right, where classes are



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       separated by a period. The CLASS attribute is most commonly used

       to attach a different style to some element, but it is

       recommended that where practical class names should be picked on

       the basis of the element's semantics, as this will permit other

       uses, such as restricting search through documents by matching

       on element class names. The conventions for choosing class names

       are outside the scope of this specification. 



   CLEAR 

       When there is already a figure or table in the margin, you

       sometimes want to position another figure below the figure in

       the margin rather than alongside it. The CLEAR attribute allows

       you to move down unconditionally:

       

       



       clear=left

           move down until left margin is clear 



       clear=right

           move down until right margin is clear 



       clear=all

           move down until both margins are clear 



       Alternatively, you can decide to place the figure alongside the

       figure in the margin just so long as there is enough room. The

       minimum width needed is specified as:

       

       



       clear="40 en"

           move down until there is at least 40 en units free 



       clear="100 pixels"

           move down until there is at least 100 pixels free 



       The style sheet (or browser defaults) may provide default

       minimum widths for each class of block-like elements. 



   NOFLOW 

       The presence of this attribute disables text flow around the

       figure. It avoids the need to use the CLEAR or NEEDS attributes

       on the following element. 



   SRC 

       Specifies the figure's graphical content. The image is specified

       as a URI. This attribute may appear together with the MD

       attribute. 



   MD 

       Specifies a message digest or cryptographic checksum for the

       associated graphic specified by the SRC attribute. It is used



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       when you want to be sure that a linked object is indeed the same

       one that the author intended, and hasn't been modified in any

       way. For instance, MD="md5:jV2OfH+nnXHU8bnkPAad/mSQlTDZ", which

       specifies an MD5 checksum encoded as a base64 character string.

       The MD attribute is generally allowed for all elements which

       support URI based links. 



   ALIGN 

       Specifies horizontal alignment of the figure:

       

       



       BLEEDLEFT 

           Flush left with the left (window) border. 



       LEFT 

           Flush left with the left text margin. 



       CENTER 

           The figure is centered between the text margins and text

           flow around the figure is disabled. This is the default

           setting for ALIGN. 



       RIGHT 

           Flush right with the right text margin. 



       BLEEDRIGHT 

           Flush right with the right (window) border 



       JUSTIFY 

           When applicable the figure should be magnified or reduced to

           fill the space between the left and right text margins. Text

           flow around the figure is disabled for align=justify. 



   WIDTH 

       Specifies the desired width in pixels or en units (according to

       the value of the UNITS attribute). User agents may scale the

       figure image to match this width. 



   HEIGHT 

       Specifies the desired height in pixels or en units (according to

       the value of the UNITS attribute). User agents may scale the

       figure image to match this height. 



   UNITS 

       Specifies the choice of units for width and height. units=pixels

       (the default) specifies pixels, while units=en specifies en

       units. The en unit is a typographical unit equal to half the

       point size. 



   IMAGEMAP 

       Specifies a URI for processing image clicks and drags. 





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Figure Overlays



   Permitted Context: start of FIG element

   Content Model: Empty! 



   The OVERLAY element is used to overlay images on top of a base

   figure. Figure overlays provide for more effective use of caching as

   small changes to a figure in a subsequent document incur only the

   penalty of downloading the overlays and not the larger base figure,

   as the latter is already in the cache. The overlay can be offset

   from the top left corner of the base image. 



Permitted Attributes



   SRC 

       Specifies the overlay image as a URI. This attribute may appear

       together with the MD attribute. 



   MD 

       Specifies a message digest or cryptographic checksum for the

       associated graphic specified by the SRC attribute. It is used

       when you want to be sure that a linked object is indeed the same

       one that the author intended, and hasn't been modified in any

       way. For instance, MD="md5:jV2OfH+nnXHU8bnkPAad/mSQlTDZ", which

       specifies an MD5 checksum encoded as a base64 character string.

       The MD attribute is generally allowed for all elements which

       support URI based links. 



   UNITS 

       Specifies the choice of units for width and height: units=pixels

       (the default) specifies pixels, while units=en specifies en

       units (a typographical unit equal to half the point size). 



   X 

       The X offset from the top left corner of the base image. X

       increases to the right, and is given in pixels or en units

       (according to the value of the UNITS attribute). 



   Y 

       The Y offset from the top left corner of the base image. Y

       increases downwards, and is given in pixels or en units

       (according to the value of the UNITS attribute). 



   WIDTH 

       Specifies the desired width in pixels or en units (according to

       the value of the UNITS attribute). User agents may scale the

       figure image to match this width. 



   HEIGHT 

       Specifies the desired height in pixels or en units (according to

       the value of the UNITS attribute). User agents may scale the

       figure image to match this height. 





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   IMAGEMAP 

       Specifies a URI for processing image clicks and drags. 









































































































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Captions



   Permitted Context: TABLE or FIG

   Content Model: %text 



   The CAPTION element is used to label a table or figure. Use the

   align attribute to specify the position of the caption relative to

   the table/figure. For example: 



       <CAPTION ALIGN=LEFT>The Niagara Falls</CAPTION>



   --Should we provide separate align and valign attributes for

   controlling the horizontal and vertical positioning respectively?-- 



Permitted Attributes



   ID 

       An SGML identifier used as the target for hypertext links or for

       naming particular elements in associated style sheets.

       Identifiers are NAME tokens and must be unique within the scope

       of the current document. 



   LANG 

       This is one of the ISO standard language abbreviations, e.g.

       "en.uk" for the variation of English spoken in the United

       Kingdom. It can be used by parsers to select language specific

       choices for quotation marks, ligatures and hypenation rules etc.

       The language attribute is composed from the two letter language

       code from ISO 639, optionally followed by a period and a two

       letter country code from ISO 3166. 



   CLASS 

       This a space separated list of SGML NAME tokens and is used to

       subclass tag names. By convention, the class names are

       interpreted hierarchically, with the most general class on the

       left and the most specific on the right, where classes are

       separated by a period. The CLASS attribute is most commonly used

       to attach a different style to some element, but it is

       recommended that where practical class names should be picked on

       the basis of the element's semantics, as this will permit other

       uses, such as restricting search through documents by matching

       on element class names. The conventions for choosing class names

       are outside the scope of this specification. 



   ALIGN 

       Positioning of the caption relative to the table or figure it

       labels. The permitted values are: TOP, BOTTOM, LEFT or RIGHT. 















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Credits



   Permitted Context: BQ or FIG

   Content Model: %text 



   The CREDIT element is used to name the source of a block quotation

   or figure. For example: 



       <CREDIT>The Writer by Richard Wilbur</CREDIT>



Permitted Attributes for the CREDIT Element



   ID 

       An SGML identifier used as the target for hypertext links or for

       naming particular elements in associated style sheets.

       Identifiers are NAME tokens and must be unique within the scope

       of the current document. 



   LANG 

       This is one of the ISO standard language abbreviations, e.g.

       "en.uk" for the variation of English spoken in the United

       Kingdom. It can be used by parsers to select language specific

       choices for quotation marks, ligatures and hypenation rules etc.

       The language attribute is composed from the two letter language

       code from ISO 639, optionally followed by a period and a two

       letter country code from ISO 3166. 



   CLASS 

       This a space separated list of SGML NAME tokens and is used to

       subclass tag names. By convention, the class names are

       interpreted hierarchically, with the most general class on the

       left and the most specific on the right, where classes are

       separated by a period. The CLASS attribute is most commonly used

       to attach a different style to some element, but it is

       recommended that where practical class names should be picked on

       the basis of the element's semantics, as this will permit other

       uses, such as restricting search through documents by matching

       on element class names. The conventions for choosing class names

       are outside the scope of this specification. 































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Tables



   Permitted Context: %body.content, %flow, %block

   Content Model: Optional CAPTION, then one or more table rows (TR) 



   The HTML table model has been chosen for its simplicity and

   flexibility. By default the table is automatically sized according

   to the cell contents and the current window size. The COLSPEC

   attribute can be used when needed to exert control over column

   widths, either by setting explicit widths or by specifying relative

   widths. You can also specify the table width explicitly or as a

   fraction of the current margins (see WIDTH attribute). 



   Table start with an optional caption followed one or more rows. Each

   row is formed by one or more cells, which are differentiated into

   header and data cells. Cells can be merged across rows and columns,

   and include attributes assisting rendering to speech and braille, or

   for exporting table data into databases. The model provides little

   direct support for control over appearence, for example border

   styles and margins, as these can be handled via subclassing and

   associated style sheets. 



   Tables can contain a wide range of content, such as headers, lists,

   paragraphs, forms, figures, preformatted text and even nested

   tables. When the table is flush left or right, subsequent elements

   will be flowed around the table if there is sufficient room. This

   behaviour is disabled when the --noflow-- attribute is given or the

   table align attribute is --center-- (the default), or --justify--. 



Example



   <TABLE BORDER>

     <CAPTION>A test table with merged cells</CAPTION>

     <TR><TH ROWSPAN=2><TH COLSPAN=2>Average

         <TH ROWSPAN=2>other<BR>category<TH>Misc

     <TR><TH>height<TH>weight

     <TR><TH ALIGN=LEFT>males<TD>1.9<TD>0.003

     <TR><TH ALIGN=LEFT ROWSPAN=2>females<TD>1.7<TD>0.002

   </TABLE>



   This would be rendered something like: 



                 A test table with merged cells

       /--------------------------------------------------\

       |          |      Average      |  other   |  Misc  |

       |          |-------------------| category |--------|

       |          |  height |  weight |          |        |

       |-----------------------------------------|--------|

       | males    |   1.9   |  0.003  |          |        |

       |-----------------------------------------|--------|

       | females  |   1.7   |  0.002  |          |        |

       \--------------------------------------------------/

   



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   There are several points to note: 



   *   By default, header cells are centered while data cells are flush

       left. This can be overriden by the ALIGN attribute for the cell;

       the COLSPEC attribute for the TABLE element; or the ALIGN

       attribute on the enclosing row's TR element (from the most

       specific to the least). 



   *   Cells may be empty. 



   *   Cells spanning rows contribute to the column count on each of

       the spanned rows, but only appear in the markup once (in the

       first row spanned). 



   *   If the column count for the table is greater than the number of

       cells for a given row (after including cells for spanned rows),

       the missing cells are treated as occurring on the right handside

       of the table, and rendered as empty cells. 



   *   The row count is determined by the TR elements - any rows

       implied by cells spanning rows beyond this should be ignored. 



   *   The user agent should be able to recover from a missing <TR> tag

       prior to the first row as the TH and TC elements can only occur

       within the TR element. 



   *   It is invalid to have cells overlap, see below for an example.

       In such cases, the rendering is implementation dependent. 



   An example of an invalid table: 



   <table border>

   <tr><tdrowspan=2>1<td>2<td>3<td>4<td>5

   <tr><td rowspan=2>6

   <tr><td colspan=2>7<td>8

   </table>



   which looks something like: 



       /-------------------\

       | 1 | 2 | 3 | 4 | 5 |

       |   |---------------|

       |   | 6 |   |   |   |    The cells labelled 6 and 7 overlap!

       |---|...|-----------|

       | 7 :   | 8 |   |   |

       \-------------------/



   Borderless tables are useful for layout purposes as well as their

   traditional role for tabular data, for instance with fill-out forms: 



   		       name: [John Smith        ]

   		card number: [4619 693523 20851 ]



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   		    expires: [03] / [97]

   		  telephone: [212 873 2739      ]



   This can be represented as a table with one row and two columns. The

   first column is right aligned, while the second is left aligned.

   This example could be marked up as: 



   <table&gt

     <tr valign=baseline>

     <td align=right>

       name:<br>

       card number:<br>

       expires:<br>

       telephone:

     <td align=left>

       <input name="name" size=18><br>

       <input name="cardnum" size=18><br>

       <input name="expires-month" size=2> /

       <input name="expires-year" size=2><br>

       <input name="phone" size=18><br>

   </table>

   



   The use of such techniques is one of the motivations for using

   nested tables, where borderless tables are used to layout cell

   contents for an enclosing table 



   Hint: You can achieve a similar effect to the above by using decimal

   alignment and using the DP attribute to set the alignment character

   to a convenient character, for example: 



   <table>

     <tr align=decimal dp=":">

     <td>

       name: <input name="name" size=18><br>

       card number: <input name="cardnum" size=18><br>

       expires: <input name="expires-month" size=2> /

       <input name="expires-year" size=2><br>

       telephone:<input name="phone" size=18><br>

   </table>

   



   Each line in the table is then indented so that all the colons are

   positioned under one another. 



Table Sizing Algorithm



   The default sizing algorithm requires two passes through the table

   data. In the first pass, word wrapping is disabled, and the user

   agent keeps track of the minimum and maximum width of each cell. The

   maximum width is given by the widest line. As word wrap has been

   disabled, paragraphs are treated as long lines unless broken by <BR>

   elements. The minimum width is given by the widest word or image



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   etc. taking into account leading indents and list bullets etc. In

   other words, if you were to format the cell's content in a window of

   its own, determine the minimum width you could make the window

   before things begin to be clipped. 



   The minimum and maximum cell widths are then used to determine the

   corresponding minimum and maximum widths for the columns. These in

   turn, are used to find the minimum and maximum width for the table.

   Note that cells can contain nested tables, but this doesn't

   complicate the code significantly. The next step is to assign column

   widths according to the current window size (more accurately - the

   width between the left and right margins). 



   The table borders and intercell margins need to be included in the

   assignment step. There are three cases: 



   1.  The minimum table width is equal to or wider than the available

       space. In this case, assign the minimum widths and allow the

       user to scroll horizontally. For conversion to braille, it will

       be necessary to replace the cells by references to notes

       containing their full content. By convention these appear before

       the table. 



   2.  The maximum table width fits within the available space. In this

       case, set the columns to their maximum widths. 



   3.  The maximum width of the table is greater than the available

       space, but the minimum table width is smaller. In this case,

       find the difference between the available space and the minimum

       table width, lets call it --W--. Lets also call --D-- the

       difference between maximum and minimum width of the table. 



       For each column, let --d-- be the the difference between maximum

       and minimum width of that column. Now set the column's width to

       the minimum width plus --d-- times --W-- over --D--. This makes

       columns with lots of text wider than columns with smaller

       amounts. 



   This assignment step is then repeated for nested tables. In this

   case, the width of the enclosing table's cell plays the role of the

   current window size in the above description. This process is

   repeated recursively for all nested tables. 



   If the COLSPEC attribute specifies the column widths explicitly, the

   user agent can attempt to use these values. If subsequently, one of

   the cells overflows its column width, the two pass mechanism may be

   invoked to redraw the table with more appropriate widths. If the

   attribute specifies relative widths, then the two pass model is

   always needed. 



   The column width assignment algorithm is then modified: 



   *   Explicit widths from the COLSPEC attribute should be used when



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       given, provided they are greater than the minimum column width,

       otherwise the latter should be used. 



   *   For relative widths, the surplus space --W--, as defined above,

       is divided up between the columns appropriately, ensuring that

       each column is given at least its minimum width. If --W-- is

       zero or negative, column widths should be increased over the

       minimum width to meet the relative width requirements. 



   If the table width is specified with the WIDTH attribute, the user

   agent attempts to set column widths to match. The WIDTH attribute

   should be disregarded if this results in columns having less than

   their minimum widths. 



Permitted Attributes



   ID 

       An SGML identifier used as the target for hypertext links or for

       naming particular elements in associated style sheets.

       Identifiers are NAME tokens and must be unique within the scope

       of the current document. 



   LANG 

       This is one of the ISO standard language abbreviations, e.g.

       "en.uk" for the variation of English spoken in the United

       Kingdom. It can be used by parsers to select language specific

       choices for quotation marks, ligatures and hypenation rules etc.

       The language attribute is composed from the two letter language

       code from ISO 639, optionally followed by a period and a two

       letter country code from ISO 3166. 



   CLASS 

       This a space separated list of SGML NAME tokens and is used to

       subclass tag names. By convention, the class names are

       interpreted hierarchically, with the most general class on the

       left and the most specific on the right, where classes are

       separated by a period. The CLASS attribute is most commonly used

       to attach a different style to some element, but it is

       recommended that where practical class names should be picked on

       the basis of the element's semantics, as this will permit other

       uses, such as restricting search through documents by matching

       on element class names. The conventions for choosing class names

       are outside the scope of this specification. 



   CLEAR 

       When there is a figure or another table in the margin, you

       sometimes want to start another table below the figure rather

       than alongside it. The CLEAR attribute allows you to move down unconditionally:

       

       



       clear=left

           move down until left margin is clear 



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       clear=right

           move down until right margin is clear 



       clear=all

           move down until both margins are clear 



       Alternatively, you can decide to place the table alongside the

       figure just so long as there is enough room. The minimum width

       needed is specified as:

       

       



       clear="40 en"

           move down until there is at least 40 en units free 



       clear="100 pixels"

           move down until there is at least 100 pixels free 



       The style sheet (or browser defaults) may provide default

       minimum widths for each class of block-like elements. 



   NOFLOW 

       The presence of this attribute disables text flow around the

       table. It avoids the need to use the CLEAR or NEEDS attributes

       on the following element. 



   ALIGN 

       Specifies horizontal alignment of the table (--not-- its contents):

       

       



       BLEEDLEFT 

           Flush left with the left (window) border. 



       LEFT 

           Flush left with the left text margin. 



       CENTER 

           The table is centered between the text margins and text flow

           around the table is disabled. This is the default setting

           for ALIGN. 



       RIGHT 

           Flush right with the right text margin. 



       BLEEDRIGHT 

           Flush right with the right (window) border 



       JUSTIFY 

           When applicable the table should be sized to fill the space

           between the left and right text margins. Text flow around

           the table is disabled for align=justify. 



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   UNITS 

       Specifies the choice of units for the COLSPEC attribute:

       

       



       units=en 

           Specifies en units (a typographical unit equalt to half the

           point size). This is the default setting and allows user

           agents to render the table a row at a time without waiting

           until all of the table's data has been received. 



       units=relative 

           Used to set the relative width of columns. The user agent

           sums the values to determine the proportional width of each

           column. 



       units=pixels 

           The least useful! 



       A design issue for user agents is how to handle cases where cell

       contents won't fit into the specified column widths. One

       approach is to clip the contents to the given column width,

       another is to resize the columns to fit the contents regardless

       of the COLSPEC attribute (its best to wait until all of the

       table's data has been processed before resizing). 



   COLSPEC 

       The colspec attribute is a list of column widths and alignment

       specifications. The columns are listed from left to right with a

       capital letter followed by a number, e.g. COLSPEC="L20 C8 L40".

       The letter is L for left, C for center, R for right alignment of

       cell contents. J is for justification, when feasible, otherwise

       this is treated in the same way as L for left alignment. D is

       for decimal alignment, see DP attribute. 



       Capital letters are required to avoid a particularly common

       error when a lower case L is confused with a one. Column entries

       are delimited by one or more space characters. 



       The number specifies the width in en's, pixels or as a

       fractional value of the table width, as according to the

       associated units attribute. This approach is more compact than

       used with most SGML table models and chosen to simplify hand

       entry. The width attribute allows you to specify the width of

       the table in pixels, em units or as a percentage of the space

       between the current left and right margins. 



   DP 

       This specifies the character to be used for the decimal point

       with the COLSPEC attribute, e.g. dp="." (the default) or dp=",".

       The default may be altered by the language context, as set by

       the LANG attribute on enclosing elements. 



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   WIDTH 

       This specifies the width of the table according to the UNITS

       attribute. If units=relative, the width is taken as a percentage

       of the width between the current left and right margins. The

       user agent should disregard this attribute if it would result in

       columns having less than their minimum widths. 



   BORDER 

       This presence of this attribute instructs the user agent to

       render borders around tables. For instance: <TABLE BORDER>. The

       precise appearence, along with the size of margins around cells,

       can be controlled by associated style sheets, or via information

       in the STYLE element in the document head. Subclassing tables,

       rows and cells is particularly useful in this regard. 



   NOWRAP 

       The NOWRAP attribute is used when you don't want the browser to

       automatically wrap lines. You can then explicitly specify line

       breaks in paragrphs using the BR element. 





































































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Table Rows



   Permitted Context: TABLE

   Content Model: Table Cells (TH or TD) 



   The TR element acts as a container for a row of table cells defined

   with the TH or TD elements. You can set default horizontal and

   vertical alignment of cell contents for the row. You also have the

   ability to disable word wrap for the row, and thereafter use the

   <BR> element to determine line breaks and hence cell widths. 



   To assist with formatting tables to paged media, authors can

   differentiate leading and trailing rows that are to be duplicated

   when splitting tables across page boundaries. The recommended

   approach is to subclass rows using the CLASS attribute For example: 



       <TABLE BORDER COLSPEC= --...-->

         <TR CLASS=Header> --header cells ...--

         <TR CLASS=Body>   --body cells ...--

         <TR CLASS=Footer> --footer cells ...--

       </TABLE>

   



   Paged browsers when splitting a table across a page boundary, can

   then insert footer rows at the bottom of the current page and header

   rows at the top of the next page, followed by the remaining body

   rows, and the footer rows. This is repeated as necessary until all

   of the body rows have been rendered. Refinements of this scheme can

   be devised by further subclassing the rows together with an

   appropriate style sheet. 



Permitted Attributes for the TR Element



   ID 

       An SGML identifier used as the target for hypertext links or for

       naming particular elements in associated style sheets.

       Identifiers are NAME tokens and must be unique within the scope

       of the current document. 



   LANG 

       This is one of the ISO standard language abbreviations, e.g.

       "en.uk" for the variation of English spoken in the United

       Kingdom. It can be used by parsers to select language specific

       choices for quotation marks, ligatures and hypenation rules etc.

       The language attribute is composed from the two letter language

       code from ISO 639, optionally followed by a period and a two

       letter country code from ISO 3166. 



   CLASS 

       This a space separated list of SGML NAME tokens and is used to

       subclass tag names. By convention, the class names are

       interpreted hierarchically, with the most general class on the

       left and the most specific on the right, where classes are



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       separated by a period. The CLASS attribute is most commonly used

       to attach a different style to some element, but it is

       recommended that where practical class names should be picked on

       the basis of the element's semantics, as this will permit other

       uses, such as restricting search through documents by matching

       on element class names. The conventions for choosing class names

       are outside the scope of this specification. 



   ALIGN 

       The ALIGN attribute can be used to explicitly specify the

       horizontal alignment of paragraphs within a table row:

       

       



       align=left 

           Paragraphs are rendered flush left. 



       align=center 

           Paragraphs are centered. 



       align=right 

           Paragraphs are rendered flush right. 



       align=justify 

           Text lines are justified where practical, otherwise this

           gives the same effect as the align=left setting. 



       align=decimal 

           Text lines are indented such that the first occurrence of a

           decimal point on each line are aligned vertically. If a line

           doesn't contain a decimal point, the line is rendered flush

           left for data cells and centered for header cells. 



       Note: By default, header cells are centered while data cells are

       flush left. This attribute can be used to alter these defaults

       on a row by row basis. If you are specifying column alignments

       with the TABLE's COLSPEC attribute, there is no point in also

       including an ALIGN attribute with the TR element, as the latter

       will be ignored. 



   DP 

       This specifies the character to be used for the decimal point

       with the ALIGN attribute, e.g. dp="." (the default) or dp=",".

       The default may be altered by the language context, as set by

       the LANG attribute on enclosing elements. 



   VALIGN 

       The VALIGN attribute can be used to explicitly specify the

       vertical alignment of material within a table row. It is

       overridden by the VALIGN attribute on individual cells:

       

       





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       valign=top 

           The cell contents appear at the top of each cell (the

           default). 



       valign=middle 

           Cell contents are centered vertically in each cell. 



       valign=bottom 

           The cell contents appear at the bottom of each cell. 



       valign=baseline 

           This is used when you want to ensure that all cells in the

           row share the same baseline. This constraint only applies to

           the first text line for each cell. 



   NOWRAP 

       The NOWRAP attribute is used when you don't want the browser to

       automatically wrap lines. You can then explicitly specify line

       breaks in paragrphs using the BR element. 







































































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Table Cells (TH and TD)



   Permitted Context: TR

   Content Model: %body.content 



   The TH and TD elements are used for table cells. TH is used for

   table header cells while TD is used for table data cells. This

   distinction gives user agents a means to render such cells

   distinctly, for instance by using a larger or heavier font for

   header cells. It is also needed when rendering to speech. The CLASS

   attribute can be used to further differentiate cells, for instance

   into heads and subheads. This can be used together with style sheets

   to control the cell border style, and fill color etc. 



   The horizontal and vertical alignment of cell contents are

   determined by the ALIGN and VALIGN attributes respectively. In their

   absence, the alignment will be inherited from the TR element for the

   row. The COLSPEC attribute of the enclosing TABLE element provides a

   convenient way of specifying the default horizontal alignment for

   columns. 



   The AXIS and AXES attributes can be used when rendering to speech to

   provide abbreviated names for each cell's headers. Another

   application is when you want to be able to later process table

   contents to enter them into a database. Theses attributes are then

   used to give database field names. The table's class attribute

   should be used to let the software recognise which tables can be

   treated in this way. 



   Note: Disabling word wrap and using the <BR> element in order to

   control cell widths is discouraged in favor of using the table

   COLSPEC and WIDTH attributes. 



Permitted Attributes for the TH/TD Element



   ID 

       An SGML identifier used as the target for hypertext links or for

       naming particular elements in associated style sheets.

       Identifiers are NAME tokens and must be unique within the scope

       of the current document. 



   LANG 

       This is one of the ISO standard language abbreviations, e.g.

       "en.uk" for the variation of English spoken in the United

       Kingdom. It can be used by parsers to select language specific

       choices for quotation marks, ligatures and hypenation rules etc.

       The language attribute is composed from the two letter language

       code from ISO 639, optionally followed by a period and a two

       letter country code from ISO 3166. 



   CLASS 

       This a space separated list of SGML NAME tokens and is used to

       subclass tag names. By convention, the class names are



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       interpreted hierarchically, with the most general class on the

       left and the most specific on the right, where classes are

       separated by a period. The CLASS attribute is most commonly used

       to attach a different style to some element, but it is

       recommended that where practical class names should be picked on

       the basis of the element's semantics, as this will permit other

       uses, such as restricting search through documents by matching

       on element class names. The conventions for choosing class names

       are outside the scope of this specification. 



   COLSPAN 

       The number of columns spanned by this cell. This allows you to

       merge cells across columns. It defaults to 1 (one). 



   ROWSPAN 

       The number of rows spanned by this cell. This allows you to

       merge cells across rows. It defaults to 1 (one). 



   ALIGN 

       The ALIGN attribute can be used to explicitly specify the

       horizontal alignment of paragraphs within a table row:

       

       



       align=left 

           Paragraphs are rendered flush left. This is the default for

           data cells (TD). 



       align=center 

           Paragraphs are centered. This is the default for header

           cells (TH). 



       align=right 

           Paragraphs are rendered flush right. 



       align=justify 

           Text lines are justified where practical, otherwise this

           gives the same effect as the align=left setting. 



       align=decimal 

           Text lines are indented such that the first occurrence of a

           decimal point on each line are aligned vertically. If a line

           doesn't contain a decimal point, the line is rendered flush

           left for data cells and centered for header cells. 



       Note: In the absence of the ALIGN attribute, the default is

       overridden by the presence of an ALIGN attribute on the parent

       TR element, or by the COLSPEC attribute on the TABLE element.

       The COLSPEC attribute takes precedence over the TR element

       though! 



   DP 

       This specifies the character to be used for the decimal point



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       with the ALIGN attribute, e.g. dp="." (the default) or dp=",".

       The default may be altered by the language context, as set by

       the LANG attribute on enclosing elements. 



   VALIGN 

       The VALIGN attribute can be used to explicitly specify the

       vertical alignment of material within a table cell:

       

       



       valign=top 

           The cell contents appear at the top of each cell (the

           default). 



       valign=middle 

           Cell contents are centered vertically in each cell. 



       valign=bottom 

           The cell contents appear at the bottom of each cell. 



       valign=baseline 

           This is used when you want to ensure that all cells in the

           row with valign=baseline share the same baseline. This

           constraint only applies to the first text line for each

           cell. 



       Note: In the absence of the VALIGN attribute, the default can be

       overridden by the presence of a VALIGN attribute on the parent

       TR element. 



   NOWRAP 

       The NOWRAP attribute is used when you don't want the browser to

       automatically wrap lines. You can then explicitly specify line

       breaks in paragraphs using the BR element. 



   AXIS 

       This defines an abbreviated name for a header cell, which can be

       used when rendering to speech. It defaults to the cell's

       content. 



   AXES 

       This is a comma separated list of axis names which together

       identify the row and column headers that pertain to this cell.

       It is used when rendering to speech to identify the cell's

       position in the table. If missing the user agent can try to

       follow up columns and left along rows (right for some languages)

       to find the corresponding header cells. 



       Note: a subheader cell may include both attributes - using AXIS

       to name itself and AXES to name the parent header cell. When

       data cells refer to header cells with both attributes, the

       parent header cells are found by following back the head-subhead

       relationships. 



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Dave Raggett                                                           Page 91



HTML 3.0                                                       28th March 1995



HTML Math



   Permitted Context: %text

   Content Model: %math 



   The <MATH> element is used to include math expressions in the

   current line. HTML math is powerful enough to describe the range of

   math expressions you can create in common word processing packages,

   as well as being suitable for rendering to speech. When rendering to

   fixed pitch text-only media, simple text graphics can be used for

   math symbols such as the integration sign, while other symbols can

   be rendered using their entity names. The SGML SHORTREF capability

   is used to provide abbreviations for hidden brackets, subscripts and

   superscripts. 



   The design of HTML math owes a lot to LaTeX's math mode, which has

   been found to be effective for a wide variety of mathematical

   typesetting. Where practical, HTML math uses tag names matching

   LaTeX commands, e.g. ATOP, CHOOSE and SQRT act in the same way as

   their LaTeX namesakes. Of course, SGML and LaTeX have quite

   different syntactical conventions. As a result, HTML math uses the

   ISO entity names for symbols rather than the TeX names. In LaTeX,

   the character command ^ sets the next character as an exponent,

   while the character command _ sets it as an index. If the exponent

   or index contains more than one character then the group of

   characters must be enclosed in curly brackets { }. This syntax is

   inappropriate for SGML, so HTML math instead treats _ and ^ as

   shortref characters for the SUB and SUP elements which are used for

   indices and exponents, respectively. 



   --I can't find the ISO entity names for the _ and ^ chararacters!-- 



   HTML math has been designed to be both concise and comparatively

   easy to read. In practice, formulae will be a little longer than in

   LaTeX, but much shorter than with other math proposals for SGML, for

   instance EuroMath or ISO 12083. This simplification has been

   achieved through the power of the BOX element, which replaces many

   elements in other proposals, as well as the simple conventions for

   binding the SUB and SUP elements and their use as generic raising

   and lowering operators. HTML math differentiates terms e.g. binary

   operators, variables, constants, integral signs, delimiters and so

   on. This simplifies rendering and reflects the assumptions adopted

   by LaTeX. It further allows the same raising and lowering operators

   to be used for many different roles according to the term they apply

   to. HTML math doesn't provide direct support for multi-line

   equations, as this can be effectively handled by combining math with

   the TABLE element. 



   Example - the integral from a to b of f(x) over 1+x 



       <MATH>&int;_a_^b^{f(x)<over>1+x} dx</MATH>



   which can be rendered on a fixed pitch text-only medium as: 



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            b

            /   f(x)

            | ------- dx

            /  1 + x

            a



   The example uses { and } as shortrefs for <BOX> and </BOX>

   respectively. This is used for invisible brackets, stretchy

   delimiters and integral signs, and placing one thing over another.

   The shortref characters "_" and "^" are used for subscripts and

   superscripts respectively. 



   HTML math follows general practice in mathematical typesetting by

   rendering functions, numbers and other constants in an upright font,

   while variables are rendered in an italic font. You can set

   particular terms in a bold face, and for chemical formulae, you can

   force the use of an upright font. Limits for symbols like the

   integral and summation signs are placed directly above (below) the

   symbol or to the immediate right depending on the symbol. 



   Spacing between constants, variables and operators is determined

   automatically. Additional spacing can be inserted with entities such

   as &thinsp; &sp; and &quadsp;. White space in the markup is used

   only to delimit adjacent variables or constants. You don't need

   spaces before or after binary operators or other special symbols, as

   these are recognised by the HTML math tokeniser. White space can be

   useful, though, for increased legibility while authoring.

   --I need to check on the ISO entity names for spacing!-- 



Math Markup



   The following elements are permitted within MATH elements: 



   BOX 

       Used for hidden brackets, stretchy delimiters, and placing one

       expression over another (e.g. numerators and denominators). 



   SUB, SUP 

       Subscripts and superscripts. Also used for limits. 



   ABOVE 

       Used to draw an arrow, line or symbol above an expression. 



   BELOW 

       Used to draw an arrow, line or symbol below an expression. 



   VEC, BAR, DOT, DDOT, HAT, TILDE 

       These are convenience tags for common accents as an alternative

       to using ABOVE. 



   SQRT, ROOT 

       For square roots and other roots of an expression. 



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   ARRAY 

       For matrices and other kinds of arrays. 



   TEXT 

       Used to include a short piece of text within a math element, and

       often combined with SUB or SUP elements. 



   B, T, BT 

       These elements are used override the default rendering. B

       renders the enclosed expression in an bold face. T designates a

       term to be rendered in an upright font, while BT designates a

       term to be rendered in a bold upright font. The class attribute

       can be used to describe the kind of term, e.g. vector, tensor,

       or matrix. 



HTML Math Entities



   *   Functions 



   *   Operators 



   *   Continuation dots 



   *   Greek letters 



   *   Relations 



   *   Accents, arrows and pointers 



   *   Delimiters 



   *   Other symbols. 



   *   Spacing entities. 



Rendering HTML Math



   The expression is rendered in three steps: 



   1.  The first step recursively parses expressions building up a

       matching hierarchy of data structures (with bounding boxes)

       corresponding to sequences of nested expressions. The math

       tokeniser needs to be able to distinguish constants, variables,

       functions, operators, delimiters, and special symbols such as

       integrals, which can take limits and may be stretchy. 



   2.  The next step sets the size of the innermost expressions based

       on the size of available fonts. If possible subscript and

       superscript expressions should be set in a smaller font. The

       size and relative positioning of neighboring and enclosing

       expressions is then propagated up the hierarchy from the

       innermost outwards, as the procedure stack formed in step (1)



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       unwinds. 



   3.  The final step is to render the hierarchy of expressions to the

       output medium. This is now straight forward as all the

       positioning and sizes of special symbols and text strings are

       now fixed. 



   Note: In practice, only a limited range of font sizes are suitable,

   as a result, deeply nested expressions like continued fractions

   can't use ever smaller fonts. This is simply handled by a parameter

   to the --ParseExpression-- routine that sets the font size to be

   used for that expression. ParseExpression is called recursively for

   nested expressions and uses the next smaller font until it bottoms

   out with the smallest font available. The size parameter corresponds

   to an enumeration of the available font sizes. 



Permitted Attributes



   ID 

       An SGML identifier used as the target for hypertext links or for

       naming particular elements in associated style sheets.

       Identifiers are NAME tokens and must be unique within the scope

       of the current document. 



   CLASS 

       This a space separated list of SGML NAME tokens and is used to

       subclass tag names. By convention, the class names are

       interpreted hierarchically, with the most general class on the

       left and the most specific on the right, where classes are

       separated by a period. 



       For the MATH element, CLASS can be used to describe the kind of

       math expression involved. This can be used to alter the way

       formulae are rendered, and to support exporting the expression

       to symbolic math software. The class "chem" is useful for

       chemical formulae which use an upright font for variables rather

       than the default italic font. For example: 



           <math class=chem> Fe_2_^2+^Cr_2_O_4_</math>



                               2+

       which is rendered as  Fe  Cr  O

                               2   2  4



       Otherwise, the conventions for choosing class names are outside

       the scope of this specification. 



   BOX 

       The presence of this attribute causes the user agent to draw a

       rectangular box around the formulae. 









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The BOX element



   Permitted Context: %math

   Content Model: %math?, LEFT?, expression, RIGHT?, %math?

   where expression is %math or %math --tag-- %math, see below. 



   The BOX element is used for a variety of purposes: 



   *   As invisible brackets for disambiguating expressions. 



   *   For placing numerators over denominators, with or without

       dividing lines, corresponding to LaTeX's --frac, atop-- and

       --choose-- commands. 



   *   For placing delimiters before, and/or after an expression, which

       grow to match the height of the expression. This corresponds to

       LaTeX's --left-- and --right-- commands. 



   *   For stretchy integral and related signs that grow to match the

       height of the integrand. This goes beyond LaTeX and avoids the

       need for different symbols for different sizes of integral signs

       etc. 



   The SHORTREF characters { and } are used as abbreviations for the

   start and end tags for BOX elements. Use the SGML entities &lcub;

   and &rcub; respectively when you need to use these characters

   literally. 



   Short fractions, are best represented using the slash character / as

   in <math>(n + m)/2</math> for (n + m)/2. For more complicated

   fractions you can use the BOX element with the OVER tag, as in: 



            1

          -----          {1<over>x + y}

          x + y

   

          x - y

        ---------        {x - y<over>1 + {a - b<over>a + b}}

            a - b

        1 + -----

            a + b

   



   Use the ATOP tag when you want to place one thing above another, but

   without the dividing line. With the CHOOSE tag, the expressions are

   also enclosed within round brackets, for instance: 



          a - b

                                     {a - b<atop>a + b}

          a + b

          

   

     (n + 1)   ( n )   (  n  )       {n+1<choose>k}



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     (     ) = (   ) + (     )          = {n<choose>k}

     (  k  )   ( k )   (k - 1)             + {n<choose>k-1}

   



   The BOX element can be used with the LEFT and RIGHT tags for

   delimiters that stretch to match the size of the enclosed

   expression. You are free to give only one or both of the delimiters,

   and you can use different symbols for the left and right. Left

   delimiters should be given before the LEFT tag, while right

   delimiters should be given following the RIGHT tag, for instance: 



                 ( 1 + x )       f(x) = {(<left>

          f(x) = ( ----- )                 1+x<over> sin x

                 ( sin x )                  <right>)}



   For curly brackets you will need to use the &lcub; and &rcub;

   entities for { and } respectively. The SIZE attribute can be used to

   get oversized delimiters, for instance: 



            2 |          |

       omega  |          |        {&omega;^2^<over>c^2^}

       -----  |<j| mu |i>|         <box size=huge> | <left>

          2   |      z   |              &lt;j | &mu;_z_ | i&gt;

         c    |          |           <right> | </box>



   The full tag name for the BOX element is needed above in order to

   specify a value for the SIZE attribute. The BOX element is also

   useful for stretching integral signs to match the height of the

   integrand. The integral and its limits appear in the position of the

   left delimiter for the BOX element. You can also include multiple

   integrals, for instance: 



      inf inf

       /   /  f(x, y)           {&int;_0_^&inf;^ &int;_0_^&inf;^<left>

       |   | --------- dx dy        f(x,y)<over>x^2^ + y^2^} dx dy

       |   |   2     2

       /   /  x  +  y

       0   0



Permitted Attributes for the BOX element



   SIZE 

       This used to obtain oversized delimiters. The permitted values

       are --normal-- (the default), --medium--, --large-- and

       --huge--. 



   Note: there are no attributes for the LEFT, RIGHT, OVER, ATOP and

   CHOOSE tags.  













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SUB and SUP



   Permitted Context: %math

   Content Model: %math 



   The SUB and SUP elements are used for subscripts and superscripts

   respectively, and are preferably rendered in reduced font. For

   integral and related signs the SUB and SUP elements are used for the

   lower and upper limits, for instance: 



      &sum;<sub>n = 0</sub><sup>&inf;</sup>



   which renders to (within limits of ascii art): 



     infinity

       ---

       \

       /

       ---

      n = 0



   The SGML SHORTREF characters "_" and "^" can be used as

   abbreviations. The above example is abbreviated to: 



       &sum;_n = 0_^&inf;^



   --Need to give entity names for when you need the _ and ^

   characters!-- 



   You have to revert to the full form of the tags when superscripting

   a superscript or subscripting a subscript, as in: 



       X<sub>a<sub>i</sub></sub>  which is  X    

                                             a   

                                              i                     

   



   You can also use superscripts to place expressions or words over

   binary operators, for instance in the following chemical reaction: 



       4LiH + AlCl_3_ &rarr;^ether^ LiAlH_4_ + 3LiCl



   which renders as: 



                      ether

        4LiH + AlCl  ------>  LiAlH  +  3LiCl

            3                      4



   The superscript is centered over the operator, and when feasible the

   operator stretched to match the width of the superscript. 



   Note: Dont' use the shortrefs for SUB and SUP in normal text - they

   only work within MATH elements! 



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Placement of subscripts and superscripts



   Some times you will want to place superscripts to the left of a

   term. The simplest way to do this is with shortrefs, e.g. 



       _4_^9^Be + _2^4^He &rarr; _6_^12^C + _0_^1^n



   which renders to (within limits of ascii art): 



        9      4        12    1

         Be +   He  -->   C +  n

        4      2         6    0



   Subscripts and superscripts immediately before a term are rendered

   to the left of the term, where as subscripts and superscripts

   immediately after a term are rendered on its right. Opportunities

   for confusion arise when scripts for a preceding term are followed

   by scripts for another term. The simplest solution is to use

   whitespace to disambiguate the situation. For instance: 



                         b                           b

       X_a_ ^b^Y  is  X   Y   while  X_a_^b^Y   is  X   Y

                       a                             a

                                              a  b

       but both X^a^ ^b^Y and X^a^^b^Y  are  X    Y   

   



   The last case is disambiguated because the two superscript elements

   can't both apply to the preceding term, as they can't both be drawn

   in the same position. The same would apply to two subscript

   elements. If in any doubt, its wise to insert a space to make your

   meaning clear! If you prefer, you can use curly brackets, as in:

   {X_a_}{^b^Y}. These brackets are shortrefs for the BOX element and

   don't appear when the expression is finally rendered. 



   The same rules apply when you use the full form of the SUB and SUP

   elements. The ALIGN attribute can be used to override the default

   position to render the script, which is normally taken from whether

   the script element precedes or follows the term to which it applies.

   For instance: 



       X<sub align=right>a</sub> <sup align=left>b</sup>Y

       X<sub align=right>a</sub>Y<sup align=left>b</sup>

       

                             b

       both render to    X    Y

                          a

   

       while  X<sub align=right>a</sub><sup align=left>b</sup>Y

   

                       b

       renders to       X   Y



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                         a

   



   In the last case, the SUP element act as a prefix superscript to X

   as there isn't a delimiter between it and the preceding SUB element.

   If in doubt, you should use brackets or whitespace to disambiguate

   the binding. 



Permitted Attributes



   The ID, LANG and CLASS attributes for SUB and SUP are not used

   within MATH elements. 



   ALIGN 

       Subscripts and superscripts are normally placed to the right of

       the term to which they apply, while limits are normally placed

       above (or below) the symbol they apply to. The ALIGN attribute

       can be used to override the default positioning. 

       

       



       align=left 

           The script (or limit) is placed to the left of the term. 



       align=center 

           The script is centered on the term and placed below it for

           subscripts, and above it (for superscipts). 



       align=right 

           The scripts are placed to the right of the term. 



       For example, you can force limits on integral signs to appear on

       the right rather than centered on the integral sign: 



       &int;<sub align=right>0</sub><sup align=right>&inf;</sup>



       Note: The ALIGN attribute should be ignored by user agents for

       the SUB and SUP elements except within MATH elements. 

































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The ABOVE element



   Permitted Context: %math

   Content Model: %math 



   The <ABOVE> element is used to draw a line, arrow, curly bracket, or

   accent --above-- the expression enclosed by this element. Stretchy

   symbols should be stretched to match the width of the enclosed

   expression. For example: 



                                        _____

       <above>X + Y</above>    giving   X + Y

   

                                                  =====

       <above sym=equals>X + Y</above>   giving   X + Y

   



   You can also place an expression centered above the line or arrow

   with the SUP element or its shortref form, for example: 



   <above sym=cub>n(n - 1)(n - 2)&dots;(n - m + 1)</above>

   <sup><text>total of m factors</text></sup>

   



   which would be rendered as (within limits of ascii art): 



              total of m factors

       /---------------^-------------\

       n(n - 1)(n - 2) ... (n - m + 1)



Permitted Attributes



   SYM 

       An entity name for a symbol, e.g. --cub-- for a curly bracket

       (brace). Defaults to --line--. The other choices are: --larr--

       (left arrow), --rarr-- (right arrow), --hat-- and --tilde--. 



   Note: Don't include the & prefix, so <above sym="&rarr;"> is wrong!  

































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HTML 3.0                                                       28th March 1995



The BELOW element



   Permitted Context: %math

   Content Model: %math 



   The <BELOW> element is used to draw a line, arrow, or curly bracket

   --below-- the expression enclosed by this element. For example: 



   

       <below>X + Y</below>    giving   X + Y

                                        _____

   

       <below sym=rarr>X + Y</below>   giving   X + Y

                                                ---->

   



   You can also place an expression centered below the line or arrow

   with the SUP element or its shortref form, for example: 



   <above sym=cub>n(n - 1)(n - 2)&dots;(n - m + 1)</above>

   <sup><text>total of m factors</text></sup>

   



   which would be rendered as (within limits of ascii art): 



       n(n - 1)(n - 2) ... (n - m + 1)

       \---------------v-------------/

              total of m factors



   --I can't find the ISO entity names for under/over curly brackets!-- 



Permitted Attributes



   SYM 

       An entity name for a stretchy symbol, e.g. --cub-- for a curly

       bracket (brace). Defaults to --line--. The other choices are:

       --larr-- (left arrow), --rarr-- (right arrow), --hat-- and

       --tilde--. 



   Note: Don't include the & prefix, so <below sym="&rarr;"> is wrong!  





























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HTML 3.0                                                       28th March 1995



VEC, BAR, DOT, DDOT, HAT and TILDE



   Permitted Context: %math

   Content Model: %math 



   These elements place an accent above the term enclosed by the

   element. --VEC-- draws a right arrow above the term; --BAR-- draws a

   line; --DOT-- and --DDOT-- draw a single and double dot

   respectively; --HAT-- and --TILDE-- draw the corresponding character

   above the term, for example: 



                               ^

       <HAT>X</HAT>   giving   X

       

                                   ~

       <TILDE>X</TILDE>   giving   X



   Note: there are no attributes for these elements.  









































































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SQRT



   Permitted Context: %math

   Content Model: %math 



   This draws a square root sign around the contents, for example the

   square root of 1 + x is expressed as: 



       <SQRT>1 + x</SQRT>



   and possibly rendered as: --(this is the best I can do with ascii

   art!)-- 



         ----------

        / 1 + x

       v



   The SQRT element has no attributes. 



ROOT



   Permitted Context: %math

   Content Model: %math, OF, %math 



   This allows you to specify arbitary roots of an expression. The

   radix comes first, and is separated from the radicand by the <OF>

   tag. For example the cube root of 1 + x is expressed as: 



       <ROOT>3<OF>1 + x</ROOT>



   and possibly rendered as: 



         --------

       3/ 1 + x

       v



   The ROOT element has no attributes.  



































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HTML 3.0                                                       28th March 1995



The ARRAY element



   Permitted Context: %math

   Content Model: one or more ROWs, each containing one or more ITEMs 



   The <ARRAY> element is used for LaTeX-like arrays. It can only be

   used within MATH elements. For example: 



       a      a    ...   a

        11     12         1n

        

       :      :    ...    :

   

       a      a    ...   a

        n1     n2         nn

   



   This is represented in HTML math by: 



       <array>

        <row><item>a_11_<item>a_12_<item>&cdots;<item>a_1n_

        <row><item>&vdots;<item>&vdots;<item>&ddots;<item>&vdots;

        <row><item>a_n1_<item>a_n2_<item>&cdots;<item>a_nn_

       </array>

   



   You can specify the "+", "-" or "=" characters as column separators: 



       a   x   +  a   x   +  ...  +  a   x    =   b

        11  1      12  2              1n  n        1

   

       a   x   +  a   x   +  ...  +  a   x    =   b

        22  1      22  2              2n  n        2

    

       .............................................

   

       a   x   +  a   x   +  ...  +  a   x    =   b

        n2  1      n2  2              nn  n        n



   This is represented by: 



   <array coldef="C+C+C+C=C">

    <row><item>a_11_x_1_<item>a_12_x_2_<item>&cdots;<item>a_1n_x_n_<item>b_1_

    <row><item>a_21_x_1_<item>a_22_x_2_<item>&cdots;<item>a_2n_x_n_<item>b_2_

    <row><item colspan=5>&dotfill;

    <row><item>a_n1_x_1_<item>a_n2_x_2_<item>&cdots;<item>a_nn_x_n_<item>b_n_

   </array>



   The number of rows and colums is left to the parser to work out for

   itself by counting the number of ROW elements, and the number of

   ITEMs on each row. This is slightly complicated by the possibility

   that some items may span several rows and columns. If a row has less

   than the expected number of items after accounting for merged items,



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   the missing items are assumed to be on the righthandside, and should

   be treated as empty. The row count should be based on the ROW

   elements, and additional rows, implied by items spanning rows beyond

   the end of the array, should be ignored. 



Permitted Attributes



   ALIGN 

       By default, arrays are vertically positioned so that preceding

       and following expressions are aligned with the mid point of the

       array. The ALIGN attribute can take on of the following values:

       

       



       TOP 

           The top row of the array is aligned with the same baseline

           as the preceding or following expression. 



       MIDDLE 

           The middle row of the array is aligned with the same

           baseline as the preceding or following expression. This is

           the default. If there are an even number of rows, the

           midpoint of the array is used instead. 



       BOTTOM 

           The bottom row of the array is aligned with the same

           baseline as the preceding or following expression. 



   COLDEF 

       By default the columns are centered. This attribute can be used

       to specify the horizontal alignment for each column with

       character string formed by one capital letter per column, with L

       for left, C for center and R to right alignment, e.g. "LLCR" for

       a 4 column table. 



       The COLDEF attribute can also be used to place a "+", "-" or "="

       between the columns, e.g. coldef="C+C+C+C=C". Whitespace within

       the COLDEF attribute is ignored. 



   LDELIM 

       An entity or character for the left delimiter, e.g. ldelim="["

       for a left square bracket or ldelim="|". The default is no

       delimiter. 



   RDELIM 

       An entity name or character for the right delimiter, e.g.

       rdelim="}" or rdelim="|". The default is no delimiter. 



   LABELS 

       The presence of this attribute has the same effect as TeX's

       bordermatrix command. The first row and column are separated

       from the rest of the array. 





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   Example of a labelled array: 



         i     j     k

         

    a  (X     X     X  )

       ( 11    21    31)    <array ldelim="(" rdelim=")" labels>

       (               )     <row><item>dummy<item>i<item>j<item>k

    b  (X     X     X  )     <row><item>a<item>X_11_<item>X_21_<item>X_31_

       ( 12    22    32)     <row><item>b<item>X_12_<item>X_22_<item>X_32_

       (               )     <row><item>c<item>X_31_<item>X_32_<item>X_33_

    c  (X     X     X  )    </array>

       ( 13    23    33)

   



   Note: An item is always required for the first item of the first

   row, although its contents will be ignored for labelled arrays. This

   has been emphasized above with the value "dummy".  











































































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HTML 3.0                                                       28th March 1995



The ROW element



   Permitted Context: ARRAY

   Content Model: one or more ITEMs 



   The <ROW> element is used for rows of items within the ARRAY

   element. It has no permitted attributes. The end tag </ROW> can

   always be left out. 



The ITEM element



   Permitted Context: ROW

   Content Model: %math 



   The <ITEM> element is used for items within a row of the ARRAY

   element. The end tag </ITEM> can always be left out. 



Permitted Attributes for ITEM



   ALIGN 

       By default expressions in items are centered horizontally. This

       can be altered by the COLDEF attribute on the parent ARRAY

       element, and overridden on a per item basis with the ALIGN

       attribute. The permitted values are: LEFT, CENTER or RIGHT. 



   COLSPAN 

       This can be used to provide a single item which spans several

       columns. The attribute value is a positive integer and defaults

       to one. 



   ROWSPAN 

       This can be used to provide a single item which spans several

       rows. The attribute value is a positive integer and defaults to

       one. It can be used together with the COLSPAN attribute. 









































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HTML 3.0                                                       28th March 1995



TEXT



   Permitted Context: %math

   Content Model: PCDATA 



   This element is used to include a few words of text within MATH

   elements. It avoids the need to separate words with spacing entities

   such as &sp; that are otherwise needed to provide adequate spacing.

   The text is rendered literally, and may include entities for

   accented characters etc. 



   There are no attributes for this element.  





















































































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B, T and BT



   Permitted Context: %math

   Content Model: %math 



   These elements are used, when feasible, to alter the default fonts

   used to render variables and constants. Numbers, operators,

   delimiters and other symbols are unaffected. B renders its contents

   in bold, while T renders its contents in an upright font rather than

   an italic font. These can be nested to combine the effects, for a

   bold upright font. The BT element allows you to write

   <BT>--term--</BT> rather from having to write:

   <B><T>--term--</T></B>. 



Permitted Attributes



   CLASS 

       This a space separated list of SGML NAME tokens and is used to

       subclass tag names. By convention, the class names are

       interpreted hierarchically, with the most general class on the

       left and the most specific on the right, where classes are

       separated by a period. 



       By using CLASS to describe the term as a --vector--, --tensor--

       or --matrix-- etc. user agents can do a better job when

       rendering to non-visual media. Further conventions for term

       class names are not part of this specification. 



   Note: Don't use B for chemical formulae. These should be handled by

   subclassing the MATH element with class=chem, for instance: <MATH

   CLASS=CHEM>  















































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HTML 3.0                                                       28th March 1995



Horizontal Rules



   Permitted Context: %Body.Content

   Content Model: Empty! 



   The <HR> element is used for horizontal rules that act as dividers

   between sections. The SRC attribute can be used to designate a

   custom graphic, otherwise subclass HR with the CLASS attribute and

   specify the appropriate rendering with an associated style sheet. 



Permitted Attributes



   ID 

       An SGML identifier used as the target for hypertext links or for

       naming particular elements in associated style sheets.

       Identifiers are NAME tokens and must be unique within the scope

       of the current document. 



   CLASS 

       This a space separated list of SGML NAME tokens and is used to

       subclass tag names. For instance, <H2 CLASS=Section> defines a

       level 2 header that acts as a section header. By convention, the

       class names are interpreted hierarchically, with the most

       general class on the left and the most specific on the right,

       where classes are separated by a period. The CLASS attribute is

       most commonly used to attach a different style to some element,

       but it is recommended that where practical class names should be

       picked on the basis of the element's semantics, as this will

       permit other uses, such as restricting search through documents

       by matching on element class names. The conventions for choosing

       class names are outside the scope of this specification. 



   CLEAR 

       This attribute is common to all block-like elements. When text

       flows around a figure or table in the margin, you sometimes want

       to position the rule below the figure rather than alongside it.

       The CLEAR attribute allows you to move down unconditionally:

       

       



       clear=left

           move down until left margin is clear 



       clear=right

           move down until right margin is clear 



       clear=all

           move down until both margins are clear 



       Alternatively, you can decide to place the rule alongside the

       figure just so long as there is enough room. The minimum width

       needed is specified as:

       



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       clear="40 en"

           move down until there is at least 40 en units free 



       clear="100 pixels"

           move down until there is at least 100 pixels free 



       The style sheet (or browser defaults) may provide default

       minimum widths for each class of block-like elements. 



   SRC 

       Specifies a custom image for the rule. The image is specified as

       a URI. This attribute may appear together with the MD attribute. 



   MD 

       Specifies a message digest or cryptographic checksum for the

       associated graphic specified by the SRC attribute. It is used

       when you want to be sure that a linked object is indeed the same

       one that the author intended, and hasn't been modified in any

       way. For instance, MD="md5:jV2OfH+nnXHU8bnkPAad/mSQlTDZ", which

       specifies an MD5 checksum encoded as a base64 character string.

       The MD attribute is generally allowed for all elements which

       support URI based links. 





























































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HTML 3.0                                                       28th March 1995



Preformatted Text (PRE)



   Permitted Context: %Body.Content, %flow, %block

   Content Model: subset of %text (see DTD for details) 



   Preformatted text between the start and end PRE tag is rendered

   using a fixed with font, in addition whitespace characters are

   treated literally. The spacing and line breaks are rendered

   directly, unlike other elements, for which repeated whitespace

   chararacters are collapsed to a single space character and line

   breaks introduced automatically. 



   *   Line breaks within the text are rendered as a move to the

       beginning of the next line. The exceptions are line breaks

       immediately following the starting PRE tag or immediately

       preceding the ending PRE tag, which should be ignored. 



   *   The <P> tag should be avoided, but for robustness, user agents

       are recommended to treat these tags as line breaks. 



   *   Anchor elements, and character highlighting elements may be

       used. 



   *   FORM elements may be included, and the fixed width font

       exploited to control layout (the TAB or TABLE elements give

       similar control for normal text though). 



   *   Block-like elements such as headers, lists, FIG and TABLES

       should be avoided. 



   *   The horizontal tab character (encoded in US ASCII and ISO 8859-1

       as decimal 9) should be interpreted as the smallest nonzero

       number of spaces which will leave the number of characters so

       far on the line as a multiple of 8. Its use is deprecated! 



   For example, a verse from Shelley (To a Skylark): 



   <PRE>

          Higher still and higher

            From the earth thou springest

          Like a cloud of fire;

            The blue deep thou wingest,

   And singing still dost soar, and soaring ever singest.</PRE>



   which is rendered as: 



          Higher still and higher

            From the earth thou springest

          Like a cloud of fire;

            The blue deep thou wingest,

   And singing still dost soar, and soaring ever singest.



Permitted Attributes



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HTML 3.0                                                       28th March 1995





   ID 

       An SGML identifier used as the target for hypertext links or for

       naming particular elements in associated style sheets.

       Identifiers are NAME tokens and must be unique within the scope

       of the current document. 



   LANG 

       This is one of the ISO standard language abbreviations, e.g.

       "en.uk" for the variation of English spoken in the United

       Kingdom. It can be used by parsers to select language specific

       choices for quotation marks, ligatures and hypenation rules etc.

       The language attribute is composed from the two letter language

       code from ISO 639, optionally followed by a period and a two

       letter country code from ISO 3166. 



   CLASS 

       This a space separated list of SGML NAME tokens and is used to

       subclass tag names. By convention, the class names are

       interpreted hierarchically, with the most general class on the

       left and the most specific on the right, where classes are

       separated by a period. The CLASS attribute is most commonly used

       to attach a different style to some element, but it is

       recommended that where practical class names should be picked on

       the basis of the element's semantics, as this will permit other

       uses, such as restricting search through documents by matching

       on element class names. The conventions for choosing class names

       are outside the scope of this specification. 



   CLEAR 

       This attribute is common to all block-like elements. When text

       flows around a figure or table in the margin, you sometimes want

       to start the preformatted text below the figure rather than

       alongside it. The CLEAR attribute allows you to move down unconditionally:

       

       



       clear=left

           move down until left margin is clear 



       clear=right

           move down until right margin is clear 



       clear=all

           move down until both margins are clear 



       Alternatively, you can decide to place the element alongside the

       figure just so long as there is enough room. The minimum width

       needed is specified as:

       

       



       clear="40 en"



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HTML 3.0                                                       28th March 1995



           move down until there is at least 40 en units free 



       clear="100 pixels"

           move down until there is at least 100 pixels free 



       The style sheet (or browser defaults) may provide default

       minimum widths for each class of block-like elements. 



   WIDTH 

       This is optionally used to specify a width as a number of

       characters to try and display within the current window width.

       The user agent can exploit this suggestion to select an

       appropriate font size. The default is a width of 80 characters.

       Where the WIDTH attribute is supported, widths of 40, 80 and 132

       characters should be presented optimally, with other widths

       being rounded up. 



       --Can't we get rid of this obsolete nonsense? How many browsers

       support the WIDTH attribute anyway? -- 







































































Dave Raggett                                                          Page 115



HTML 3.0                                                       28th March 1995



Admonishments



   Permitted Context: %body.content, %flow, %block

   Content Model: %body.content 



   The NOTE element is designed for use as admonishments such as notes,

   cautions or warnings, as commonly used in technical documentation.

   The CLASS attribute specifies the type of the element and is

   typically associated with different graphics such as a road traffic

   warning sign. The graphic can be customized with the SRC attribute. 



   Example: 



       <NOTE CLASS=WARNING>Please check with the local weather

       service before starting your climb. The mountain weather

       is subject to rapid deterioration. It is essential to

       carry a good map and compass.</NOTE>



   The class names: NOTE, CAUTION and WARNING are recommended for

   standard admonishments. In the absence of the CLASS attribute, a

   NOTE element is typically rendered indented, without an accompanying

   graphic. 



Permitted Attributes



   ID 

       An SGML identifier used as the target for hypertext links or for

       naming particular elements in associated style sheets.

       Identifiers are NAME tokens and must be unique within the scope

       of the current document. 



   LANG 

       This is one of the ISO standard language abbreviations, e.g.

       "en.uk" for the variation of English spoken in the United

       Kingdom. It can be used by parsers to select language specific

       choices for quotation marks, ligatures and hypenation rules etc.

       The language attribute is composed from the two letter language

       code from ISO 639, optionally followed by a period and a two

       letter country code from ISO 3166. 



   CLASS 

       This a space separated list of SGML NAME tokens and is used to

       subclass tag names. By convention, the class names are

       interpreted hierarchically, with the most general class on the

       left and the most specific on the right, where classes are

       separated by a period. The CLASS attribute is most commonly used

       to attach a different style to some element, but it is

       recommended that where practical class names should be picked on

       the basis of the element's semantics, as this will permit other

       uses, such as restricting search through documents by matching

       on element class names. Apart from the values suggested above,

       the conventions for choosing class names are outside the scope

       of this specification. 



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   CLEAR 

       This attribute is common to all block-like elements. When text

       flows around a figure or table in the margin, you sometimes want

       to start the note below the figure rather than alongside it. The

       CLEAR attribute allows you to move down unconditionally:

       

       



       clear=left

           move down until left margin is clear 



       clear=right

           move down until right margin is clear 



       clear=all

           move down until both margins are clear 



       Alternatively, you can decide to place the note alongside the

       figure just so long as there is enough room. The minimum width

       needed is specified as:

       

       



       clear="40 en"

           move down until there is at least 40 en units free 



       clear="100 pixels"

           move down until there is at least 100 pixels free 



       The style sheet (or browser defaults) may provide default

       minimum widths for each class of block-like elements. 



   SRC 

       Specifies an image to appear preceding the note. The image is

       specified as a URI. This attribute may appear together with the

       MD attribute. 



   MD 

       Specifies a message digest or cryptographic checksum for the

       associated graphic specified by the SRC attribute. It is used

       when you want to be sure that a linked object is indeed the same

       one that the author intended, and hasn't been modified in any

       way. For instance, MD="md5:jV2OfH+nnXHU8bnkPAad/mSQlTDZ", which

       specifies an MD5 checksum encoded as a base64 character string.

       The MD attribute is generally allowed for all elements which

       support URI based links. 















Dave Raggett                                                          Page 117



HTML 3.0                                                       28th March 1995



Footnotes



   Permitted Context: %body.content, %flow, %block

   Content Model: %body.content 



   The FN element is designed for footnotes, and when practical,

   rendered as pop-up notes. 



   Example: 



   <DL>

   <DT>Hamlet: <DD>You should not have believed me, for virtue cannot

   so <a href="#fn1">inoculate</a> our old stock but we shall <a

   href="#fn2">relish of it</a>. I loved you not.

   

   <DT>Ophelia: <DD> I was the more deceived.

   

   <DT>Hamlet: <DD>Get thee to a nunnery. Why wouldst thou be a breeder

   of sinners? I am myself <a href="#fn2">indifferent honest</a> ...

   </DL> 



   <fn id=fn1><i>inoculate</i> - graft</fn>

   <fn id=fn2><i>relish of it</i> - smack of it (our old sinful nature)</fn>

   <fn id=fn3><i>indifferent honest</i> - moderately virtuous</fn> 



   Note: If %html.recommended is active, the HTML 3.0 DTD expects you

   to enclose plain text in a block element such as <P> e.g.

   

   <FN ID=fn23><P>A simple footnote</FN> 



Permitted Attributes



   ID 

       An SGML identifier used as the target for hypertext links or for

       naming particular elements in associated style sheets.

       Identifiers are NAME tokens and must be unique within the scope

       of the current document. 



   LANG 

       This is one of the ISO standard language abbreviations, e.g.

       "en.uk" for the variation of English spoken in the United

       Kingdom. It can be used by parsers to select language specific

       choices for quotation marks, ligatures and hypenation rules etc.

       The language attribute is composed from the two letter language

       code from ISO 639, optionally followed by a period and a two

       letter country code from ISO 3166. 



   CLASS 

       This a space separated list of SGML NAME tokens and is used to

       subclass tag names. By convention, the class names are

       interpreted hierarchically, with the most general class on the

       left and the most specific on the right, where classes are

       separated by a period. The CLASS attribute is most commonly used



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       to attach a different style to some element, but it is

       recommended that where practical class names should be picked on

       the basis of the element's semantics, as this will permit other

       uses, such as restricting search through documents by matching

       on element class names. The conventions for choosing class names

       are outside the scope of this specification. 

































































































Dave Raggett                                                          Page 119



HTML 3.0                                                       28th March 1995



Block Quotes



   Permitted Context: %Body.Content, %flow, %block

   Content Model: %Body.Content followed by optional CREDIT element 



   The BQ element is used for extended quotations. The tag name has

   been abbreviated from HTML 2.0's BLOCKQUOTE to the more convenient

   BQ, and the content model extended to allow the source of the

   quotation to be credited. 



   Example: 



   <BQ>

   <P>But now I shall shortly proffer him the strength and the

   courage of the Geats in combat. He who has the right to it shall

   go once more to the mead-drinking with confident heart, after

   the morning light of another day, the sun clothed in ethereal

   radiance, shines from the south upon the children of men.

   <CREDIT>Beowulf replying to Unferth, from the Anglo-Saxon poem

   "Beowolf", Cotton Vitellus A xv manuscript</CREDIT>

   </BQ>



   Note: If %html.recommended is active, the HTML 3.0 DTD expects you

   to enclose plain text in a block element such as <P> 



Permitted Attributes



   ID 

       An SGML identifier used as the target for hypertext links or for

       naming particular elements in associated style sheets.

       Identifiers are NAME tokens and must be unique within the scope

       of the current document. 



   LANG 

       This is one of the ISO standard language abbreviations, e.g.

       "en.uk" for the variation of English spoken in the United

       Kingdom. It can be used by parsers to select language specific

       choices for quotation marks, ligatures and hypenation rules etc.

       The language attribute is composed from the two letter language

       code from ISO 639, optionally followed by a period and a two

       letter country code from ISO 3166. 



   CLASS 

       This a space separated list of SGML NAME tokens and is used to

       subclass tag names. By convention, the class names are

       interpreted hierarchically, with the most general class on the

       left and the most specific on the right, where classes are

       separated by a period. The CLASS attribute is most commonly used

       to attach a different style to some element, but it is

       recommended that where practical class names should be picked on

       the basis of the element's semantics, as this will permit other

       uses, such as restricting search through documents by matching

       on element class names. The conventions for choosing class names



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       are outside the scope of this specification. 



   CLEAR 

       This attribute is common to all block-like elements. When text

       flows around a figure or table in the margin, you sometimes want

       to start the block quote below the figure rather than alongside

       it. The CLEAR attribute allows you to move down unconditionally:

       

       



       clear=left

           move down until left margin is clear 



       clear=right

           move down until right margin is clear 



       clear=all

           move down until both margins are clear 



       Alternatively, you can decide to place the quote alongside the

       figure just so long as there is enough room. The minimum width

       needed is specified as:

       

       



       clear="40 en"

           move down until there is at least 40 en units free 



       clear="100 pixels"

           move down until there is at least 100 pixels free 



       The style sheet (or browser defaults) may provide default

       minimum widths for each class of block-like elements. 



   NOWRAP 

       The NOWRAP attribute is used when you don't want the browser to

       automatically wrap lines. You can then explicitly specify line

       breaks using the BR element. 

































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The ADDRESS element



   Permitted Context: %Body.Content

   Content Model: P or %text 



   The ADDRESS element specifies such information as address, signature

   and authorship for the current document, and typically placed at the

   top or bottom of the document. When used with %text, the element

   acts similar to a paragraph with breaks before and after. 



   Example: 



   <ADDRESS>

   Newsletter editor<BR>

   J.R. Brown<BR>

   8723 Buena Vista, Smallville, CT 01234&t;BR>

   Tel: +1 (123) 456 7890

   </ADDRESS>



Permitted Attributes



   ID 

       An SGML identifier used as the target for hypertext links or for

       naming particular elements in associated style sheets.

       Identifiers are NAME tokens and must be unique within the scope

       of the current document. 



   LANG 

       This is one of the ISO standard language abbreviations, e.g.

       "en.uk" for the variation of English spoken in the United

       Kingdom. It can be used by parsers to select language specific

       choices for quotation marks, ligatures and hypenation rules etc.

       The language attribute is composed from the two letter language

       code from ISO 639, optionally followed by a period and a two

       letter country code from ISO 3166. 



   CLASS 

       This a space separated list of SGML NAME tokens and is used to

       subclass tag names. By convention, the class names are

       interpreted hierarchically, with the most general class on the

       left and the most specific on the right, where classes are

       separated by a period. The CLASS attribute is most commonly used

       to attach a different style to some element, but it is

       recommended that where practical class names should be picked on

       the basis of the element's semantics, as this will permit other

       uses, such as restricting search through documents by matching

       on element class names. The conventions for choosing class names

       are outside the scope of this specification. 



   CLEAR 

       This attribute is common to all block-like elements. When text

       flows around a figure or table in the margin, you sometimes want

       to start the address element below the figure rather than



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       alongside it. The CLEAR attribute allows you to move down unconditionally:

       

       



       clear=left

           move down until left margin is clear 



       clear=right

           move down until right margin is clear 



       clear=all

           move down until both margins are clear 



       Alternatively, you can decide to place the address alongside the

       figure just so long as there is enough room. The minimum width

       needed is specified as:

       

       



       clear="40 en"

           move down until there is at least 40 en units free 



       clear="100 pixels"

           move down until there is at least 100 pixels free 



       The style sheet (or browser defaults) may provide default

       minimum widths for each class of block-like elements. 



   NOWRAP 

       The NOWRAP attribute is used when you don't want the browser to

       automatically wrap lines. You can then explicitly specify line

       breaks using the BR element. 













































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The FORM element



   Permitted Context: %Body.Content

   Content Model: %Body.Content --plus-- INPUT, TEXTAREA, and SELECT

   Note you are not allowed to nest FORM elements! 



   HTML fill-out forms can be used for questionaires, hotel

   reservations, order forms, data entry and a wide variety of other

   applications. The form is specified as part of an HTML document. The

   user fills in the form and then --submits-- it. The user agent then

   sends the form's contents as designated by the FORM element.

   Typically, this is to an HTTP server, but you can also email form

   contents for asynchronous processing. 



   Forms are created by placing input fields within paragraphs,

   preformatted text, lists and tables. This gives considerable

   flexibility in designing the layout of forms. 



   HTML 3.0 supports the following kinds of fields: 



   *   Simple text fields 



   *   Multi-line text fields 



   *   Radio buttons 



   *   Checkboxes 



   *   Range controls (sliders, or knobs) 



   *   Single/multiple choice menus 



   *   Scribble on image 



   *   File widgets for attaching files to forms. 



   *   Submit buttons for sending form contents 



   *   Reset buttons for resetting fields to their initial values 



   *   Hidden fields for book keeping information 



   It is expected that future revisions to HTML will add support for

   audio fields, multi-row entry of database tables, and extending

   multi-line text fields to support a range of other data types, in

   addition to plain text. Client-side scripts will provide the means

   to constrain field values and to add new field types. 



Example of a form



   This fictitious example is a questionnaire. It uses the INPUT

   element for simple text fields, radio buttons, checkboxes, and the

   submit and reset buttons. The TEXTAREA field is used for a



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   multi-line text entry field. The form fields are laid out with

   several paragraph elements and an unordered list. Notice the use of

   the NAME attribute to name each field: 



   

   <TITLE>Sample Questionaire</TITLE>

   <H1>Sample Questionaire</H1>

   

   <P>Please fill out this questionaire:

   

   <FORM METHOD=post ACTION="http://www.hal.com/sample">

   <P>Your name: <input name="name" size="48">

   <P><input name="male" type=radio> Male

   <P><input name="female" type=radio>Female 

     Number in family: <input name="family" type=int>

     

   <P>Cities in which you maintain a residence:

   

   <UL PLAIN>

   <LI><input name="city" type=checkbox value="kent"> Kent

   <LI><input name="city" type=checkbox value="miami"> Miami

   <LI>Others <textarea name="other" cols=48 rows=4></textarea>

   </UL>

   

   <P>Nickname: <INPUT NAME="nickname" size ="42">

   

   <P>Thank you for responding to this questionaire.

   <P><INPUT TYPE=SUBMIT> <INPUT TYPE=RESET>

   </FORM>

   



   Every form must be enclosed within a FORM element. There can be

   several forms in a single document, but the FORM element can't be

   nested. The browser is responsible for handling the input focus,

   i.e. which field will currently get keyboard input. Many platforms

   have existing conventions for forms, for example, using Tab and

   Shift-Tab to move the keyboard focus forwards and backwards between

   fields, and using the Enter (aka Return) key to submit the form. 



   This standard defines and requires support for the HTTP access

   protocol only. Under any protocol, the submitted contents of the

   form logically consist of a list of name/value pairs where the names

   are given by the NAME attributes of the various fields in the FORM.

   Each field will normally be given a distinct name. Several radio

   buttons can share the same name, as this is how you specify that

   they belong to the same control group - at any time, only one button

   in the group can be selected. 



   Note: The contents list of name/value pairs excludes unselected

   radio buttons and checkboxes. In general, any field with a null

   value can be omitted from the contents list. 



Client-side scripts and fill-out forms



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   HTML 3.0 doesn't provide direct support for constraining the values

   entered into text fields, or for derived fields whose values are

   calculated from the values of other fields. Rather than extending

   the markup to support these features, HTML 3.0 provides a means for

   associating the form with a script. Support for scripts is not

   required, however, and the HTML 3.0 specification doesn't cover the

   scripting languages or the details of their interface with the user

   agent 



   The SCRIPT attribute of the FORM element specifies the script via a

   URI. The user agent down-loads the script and interprets it locally.

   Scripts handle a variety of messages for individual fields and the

   form as a whole. These messages correspond to events such as: 



   *   Enter/Leave Form (for initialization and clean up) 



   *   When a field gains or loses the input focus 



   *   Mouse clicks and drags over a field 



   *   Keyboard events 



   Scripts can examine and set properties of fields. They can also

   examine a small set of standard properties of the user agent, for

   instance the user's name, the time of day, the type of user agent,

   and so on. 



   Scripts can't do anything that might jeopardize the user or the host

   machine. Scripts can't send messages over the network, or read or

   write files. The library calls that are allowed are restricted to a

   very small and well defined set. These precautions are necessary for

   untrusted scripts. It is envisaged that script interpreters will

   offer a much wider application programming interface to trusted

   scripts, as determined on the basis of a digital signature by a

   trusted third party. 



Permitted Attributes for FORM



   ACTION 

       The ACTION attribute is a URL specifying the location to which

       the contents of the form is submitted to elicit a response. If

       the ACTION is missing, the URL for the document itself is

       assumed. The way data is submitted varies with the access

       protocol of the URL, and with the values of the METHOD and

       ENCTYPE attributes. 



   METHOD 

       This specifies variations in the protocol used to send the form

       contents. It is currently restricted to GET (the default) or

       POST. The attribute was introduced to inform user agents which

       HTTP methods the server supports. 





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   ENCTYPE 

       This attribute specifies the MIME content type to be used to

       encode the form contents. It defaults to the string:

       "application/x-www-form-urlencoded" 



   SCRIPT 

       This can be used to give a URI for a script. The scripting

       language and the interface with the user agent is not part of

       the HTML 3.0 specification. 



























































































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The INPUT fields



   Permitted Context: %Body.Content

   Content Model: --Empty!-- 



   The INPUT element is used for a wide variety of different kinds of

   entry fields within HTML fill-out forms. The TYPE attribute

   determines the type of field. 



Single-line text fields --(type=text)--



   These are used for entering short text strings, like peoples names,

   numbers and dates. The visible width of the field in characters can

   be set with the SIZE attribute. When using a variable pitch font,

   the SIZE attribute sets the width in en units (half the point size).

   The user should be able to enter more than this, with the contents

   of the field scrolling horizontally as needed. The MAXLENGTH

   attribute can be used to specify the maximum number of characters

   permitted for the string. 



   If the TYPE attribute is missing, the INPUT element is assumed to be

   a single-line text field. The NAME attribute is used to identify the

   field when the form's contents are converted to the name/value list.

   The VALUE field can be used to initialize the text string. Character

   entities can be used include accented characters in this string. 



   Note: Use the TEXTAREA element for multi-line text entry fields. 



Password fields --(type=password)--



   This is the same as single-line text fields except that each

   character typed is echoed by a shadow character, e.g. an asterisk or

   the space character. The user can see how many characters that have

   been typed but not what was typed. 



Checkbox fields --(type=checkbox)--



   A checkbox field has two states: selected and unselected.Its

   name/value pair only appear in the submitted data when selected.

   Checkboxes are used for boolean attributes. They can also be used

   for attributes which can take multiple values at the same time. This

   is represented by a checkbox for each optional value, with the same

   name for each of the checkboxes. Unselected checkboxes don't appear

   in the submitted data. Both NAME and VALUE are required for

   checkboxes. To initialize the checkbox to its selected state,

   include the CHECKED attribute. Checkboxes provide an alternative to

   using the SELECT element for multiple-choice menus. 



Radio Buttons --(type=radio)--



   Suitable for attributes which can take a single value from a set of

   alternatives. All radio buttons in the same group should be given

   the same NAME. Only the selected radio button in the group generates



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   a name/value pair in the submitted data. Both NAME and VALUE are

   required for radio buttons. To initialize the radio button to its

   selected state, include the CHECKED attribute. Radio buttons offer

   an alternative to using the SELECT element for single choice menus. 



Range fields --(type=range)--



   These allow the user to pick a numeric value in between a lower and

   an upper bound. The range is specified with the MIN and MAX

   attributes, as in: 



       <input name=rating type=range min=1 max=10>



   If either the lower or upper bound is a real number, then the range

   is real valued, otherwise it is restricted to integer values only.

   The VALUE attribute can be used to initialize the range field. It an

   error for the value to lie outside the specified range. The default

   value is midway between the lower and upper limits. 



Scribble on Image --(type=scribble)--



   These fields allow the user to scribble with a pointing device (such

   as a mouse or pen) on top of a predefined image. The image is

   specified as a URI with the SRC attribute. If the user agent can't

   display images, or can't provide a means for users to scribble on

   the image, then the field should be treated as a text field. The

   VALUE attribute can be used to initialize the text field for these

   users. It is ignored when the user agent provides scribble on image

   support. 



File Attachments --(type=file)--



   This allows users to attach one or more files to be submitted with

   the form's contents. The ACCEPT attribute can be used to specify a

   comma separated list of MIME content types. These are used to

   restrict the kinds of files that can be attached to the form. For

   instance: 



       <input name=pictures type=file accept="image/*">



   This example restricts files to match "image/*", i.e. to registered

   MIME image types. For windows based user agents, it is suggested

   that file fields display the name of the last file attached, with

   the ability to open a file dialog box to view the complete list of

   files attached so far. The accept attribute then acts to specify the

   filter on the list of candidate files. 



Hidden fields --(type=hidden)--



   No field is presented to the user, but the content of the field is

   sent with the submitted form. This value may be used to transmit

   state information about client/server interaction, for instance a

   transaction identifier. These fields are needed because HTTP servers



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   don't preserve state information from one request to the next. 



Submit buttons --(type=submit)--



   These are buttons that when pressed submit the form's data. You can

   use the VALUE attribute to provide a non-editable label to be

   displayed on the button. The default label is application-specific.

   A graphic can be specified for the submit button using the SRC

   attribute. 



   The submit button normally makes no contribution to the submitted

   data. The exception is when the field includes a NAME attribute, in

   which case, the name and value attributes are included with the

   submitted data. This can be used to distinguish which submit button

   the user pressed. 



Image fields --(type=image)--



   These act like submit buttons but include the location where the

   user clicked on the image. The image is specified with the SRC

   attribute. 



   --Should we phase these out, in favor of using SUBMIT? For this, we

   would need to ensure that the submit button included the location

   clicked when a graphic was specified with SRC.-- 



Reset buttons --(type=reset)--



   When a reset button is pressed, the form's fields are reset to their

   specified initial values. The label to be displayed on the button

   may be specified just as for the SUBMIT button. Likewise, the SRC

   attribute can be used to specify a graphic. 



------------------------------------------------------------------------------

Permitted Attributes for the INPUT element



   ID 

       An SGML identifier used as the target for hypertext links or for

       naming particular elements in associated style sheets.

       Identifiers are NAME tokens and must be unique within the scope

       of the current document. 



   LANG 

       This is one of the ISO standard language abbreviations, e.g.

       "en.uk" for the variation of English spoken in the United

       Kingdom. It can be used by parsers to select language specific

       choices for quotation marks, ligatures and hypenation rules etc.

       The language attribute is composed from the two letter language

       code from ISO 639, optionally followed by a period and a two

       letter country code from ISO 3166. 



   CLASS 

       This a space separated list of SGML NAME tokens and is used to



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       subclass tag names. By convention, the class names are

       interpreted hierarchically, with the most general class on the

       left and the most specific on the right, where classes are

       separated by a period. The CLASS attribute is most commonly used

       to attach a different style to some element, but it is

       recommended that where practical class names should be picked on

       the basis of the element's semantics, as this will permit other

       uses, such as restricting search through documents by matching

       on element class names. The conventions for choosing class names

       are outside the scope of this specification. 



   TYPE

       Defines the type of the field as one of: TEXT, PASSWORD,

       CHECKBOX, RADIO, RANGE, FILE, SCRIBBLE, HIDDEN, SUBMIT, IMAGE or

       RESET. It defaults to TEXT. The attribute value is an SGML name

       token and and as such is case insensitive. 



   NAME

       This provides a character string used to name the field when

       submitting the form's data. Several fields may share the same

       name, for instance a group of radio buttons or checkboxes. The

       name is case insensitive. 



   VALUE

       This is a character string or number which is used to initialize

       text, range and hidden fields. 



   DISABLED

       When present, the field should be rendered as normal, but can't

       be modified by the user. Where practical the rendering should

       provide a cue that the field is disabled e.g. by graying out the

       text, changing the color of the background or similar. 



   ERROR

       This attribute specifies an error message explaining why the

       field's current value is incorrect. When this attribute is

       missing, the field can be assumed to be ok. User agents are

       recommended to provide a cue to indicate that the field is in

       error. 



   CHECKED

       The presence of this attribute indicates that a radio button or

       checbox should be initialized to its selected state. 



   SIZE

       This specifies the visible width of a text or password field.

       For fixed pitch fonts, the size attribute specifies the maximum

       number of characters visible, while for variable pitch fonts,

       the attribute specifies the width in en units (half the point

       size). 



   MAXLENGTH

       Specifies the maximum number of characters permitted for text



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       and password fields. 



   MIN

       This is an integer or real number and specifies the lower bound

       for a range field. 



   MAX

       This is an integer or real number and specifies the upper bound

       for a range field. 



   ACCEPT

       A comma separated list of MIME content types for use in

       restricting the types of files that can be attached to a form

       with a file field. 



   SRC (Source) 

       The SRC attribute specifies the URI for an image for use as the

       background of a SCRIBBLE, IMAGE, SUBMIT or RESET field. Its

       syntax is the same as that of the HREF attribute of the <A> tag. 



   MD 

       Specifies a message digest or cryptographic checksum for the

       associated image specified by the SRC attribute. It is used when

       you want to be sure that the image is indeed the same one that

       the author intended, and hasn't been modified in any way. For

       instance, MD="md5:jV2OfH+nnXHU8bnkPAad/mSQlTDZ", which specifies

       an MD5 checksum encoded as a base64 character string. The MD

       attribute is generally allowed for all elements which support

       URI based links. 



   ALIGN 

       This attribute only applies to fields with background images,

       i.e. SCRIBBLE, IMAGE, SUBMIT or RESET fields. It is intended to

       provide the same positional control as for the IMG element. The

       ALIGN attribute takes the values TOP or MIDDLE or BOTTOM,

       defining whether the top or middle or bottom of the field should

       be aligned with the baseline for the text line in which the

       INPUT element appears. 



       With ALIGN=LEFT, the field will float down and over to the

       current left margin, and subsequent text will wrap around the

       right hand side of the field. Likewise for ALIGN=RIGHT, the

       field aligns with the current right margin and, and text wraps

       around the left. 





















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TEXTAREA



   Permitted Context: %Body.Content

   Content Model: PCDATA (i.e. text and entities) 



TEXTAREA



   To let users enter more than one line of text, use the TEXTAREA

   element. For example: 



   <TEXTAREA NAME="address" ROWS=64 COLS=6>

   HaL Computer Systems

   1315 Dell Avenue

   Campbell, California 95008

   </TEXTAREA>

   



   The text up to the end tag is used to initialize the field's value.

   The initialization text can contain SGML entities, e.g. for accented

   characters, but is otherwise treated as literal text. This end tag

   is always required even if the field is initially blank. When

   submitting a form, the line terminators are implementation

   dependent. Servers should be capable of recognizing a CR immediately

   followed by an LF, or separate CRs and LFs as all signifying the

   ends of lines. User agents should tolerate the same range of line

   terminators within the initialization text. 



   In a typical rendering, the ROWS and COLS attributes determine the

   visible dimension of the field in characters. The field is rendered

   in a fixed-width font. User agents should allow text to grow beyond

   these limits by scrolling as needed. The user agent is recommended

   to wrap words as they are entered, to fit within the textarea field.

   It is further recommended that a means is provided for users to turn

   this feature off and on. 



   Note: In the initial design for forms, multi-line text fields were

   supported by the INPUT element with TYPE=TEXT. Unfortunately, this

   causes problems for fields with long text values as SGML limits the

   length of attribute literals. The HTML 2.0 DTD allows for up to 1024

   characters (the SGML default is only 240 characters). 



Permitted Attributes



   ID 

       An SGML identifier used as the target for hypertext links or for

       naming particular elements in associated style sheets.

       Identifiers are NAME tokens and must be unique within the scope

       of the current document. 



   LANG 

       This is one of the ISO standard language abbreviations, e.g.

       "en.uk" for the variation of English spoken in the United

       Kingdom. It can be used by parsers to select language specific



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       choices for quotation marks, ligatures and hypenation rules etc.

       The language attribute is composed from the two letter language

       code from ISO 639, optionally followed by a period and a two

       letter country code from ISO 3166. 



   CLASS 

       This a space separated list of SGML NAME tokens and is used to

       subclass tag names. By convention, the class names are

       interpreted hierarchically, with the most general class on the

       left and the most specific on the right, where classes are

       separated by a period. The CLASS attribute is most commonly used

       to attach a different style to some element, but it is

       recommended that where practical class names should be picked on

       the basis of the element's semantics, as this will permit other

       uses, such as restricting search through documents by matching

       on element class names. The conventions for choosing class names

       are outside the scope of this specification. 



   NAME 

       The formal name of the field which is used in the form's

       contents list. 



   ROWS 

       This gives the visible number of text lines shown by the field.

       User agents should allow text to grow beyond these limits by

       scrolling as needed. 



   COLS 

       The visible number of characters across the field. User agents

       should allow text to grow beyond these limits by scrolling as

       needed. 



   DISABLED

       When present, the field should be rendered as normal, but can't

       be modified by the user. Where practical the rendering should

       provide a cue that the field is disabled e.g. by graying out the

       text, changing the color of the background or similar. 



   ERROR

       This attribute specifies an error message explaining why the

       field's current value is incorrect. When this attribute is

       missing, the field can be assumed to be ok. User agents are

       recommended to provide a cue to indicate that the field is in

       error. 



   ALIGN 

       Take values TOP or MIDDLE or BOTTOM, defining whether the top or

       middle or bottom row of the field should be aligned with the

       baseline for the text line in which the TEXTAREA element

       appears. The default is align=top. 



       With ALIGN=LEFT, the field will float down and over to the

       current left margin, and subsequent text will wrap around the



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       right hand side of the field. Likewise for ALIGN=RIGHT, the

       field aligns with the current right margin and, and text wraps

       around the left. 







































































































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The SELECT element



   Permitted Context: %Body.Content --but-- must be within FORM

   Content Model: one ore more OPTION elements 



   The SELECT element is used for single and multiple choice menus. It

   is generally rendered as a drop-down or pop-up menu, and offers a

   more compact alternative to using radio buttons for single choice

   menus, or checkboxes for multiple choice menus. 



   Example: 



   <SELECT NAME="flavor">

   <OPTION>Vanilla

   <OPTION>Strawberry

   <OPTION>Rum and Raisin

   <OPTION>Peach and Orange

   </SELECT>

   



   This is a single choice menu. When you want a multiple choice menu,

   you need to include the MULTIPLE attribute with the SELECT element,

   e.g. <SELECT MULTIPLE NAME="flavor">. 



   The NAME attribute is used when creating the name/value list

   describing the form's contents. A name/value pair is contributed for

   each selected option. The value is taken from the OPTION's VALUE

   attribute, and defaults to the content of the OPTION when the VALUE

   attribute is missing. 



   For single choice menus, if no option is initially marked as

   selected, then the first item listed is selected. This is

   inappropriate for multiple choice menus, though. 



Graphical Menus



   HTML 3.0 extends the SELECT element to support graphical menus. This

   is allows you to specify an image for the SELECT element, and

   hotzones for each of the OPTION elements. In this way the same menu

   can be rendered as a conventional text-based menu for non-graphical

   user agents and a graphical menu for graphical user agents. 



   The image is specified in the same way as for IMG elements. This

   means you can specify suggested values for the width and height. You

   can also float the image to the left or right margins and flow other

   elements around it. The hotzones for OPTION elements are specified

   using the SHAPE attribute in the same way as for anchor elements. 



Permitted Attributes



   ID 

       An SGML identifier used as the target for hypertext links or for

       naming particular elements in associated style sheets.



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       Identifiers are NAME tokens and must be unique within the scope

       of the current document. 



   LANG 

       This is one of the ISO standard language abbreviations, e.g.

       "en.uk" for the variation of English spoken in the United

       Kingdom. It can be used by parsers to select language specific

       choices for quotation marks, ligatures and hypenation rules etc.

       The language attribute is composed from the two letter language

       code from ISO 639, optionally followed by a period and a two

       letter country code from ISO 3166. 



   CLASS 

       This a space separated list of SGML NAME tokens and is used to

       subclass tag names. By convention, the class names are

       interpreted hierarchically, with the most general class on the

       left and the most specific on the right, where classes are

       separated by a period. The CLASS attribute is most commonly used

       to attach a different style to some element, but it is

       recommended that where practical class names should be picked on

       the basis of the element's semantics, as this will permit other

       uses, such as restricting search through documents by matching

       on element class names. The conventions for choosing class names

       are outside the scope of this specification. 



   NAME 

       The formal name of the menu which is used in the form's contents

       list. 



   MULTIPLE 

       The presence of this attribute denotes that the SELECT element

       defines a multiple choice menu. In its absence, the element

       defines a single choice menu. 



   DISABLED

       When present, the menu should be rendered as normal, but can't

       be modified by the user. Where practical the rendering should

       provide a cue that the menu is disabled e.g. by graying out the

       text, changing the color of the background or similar. 



   ERROR

       This attribute specifies an error message explaining why the

       menu's current selections are incorrect. Further error messages

       can be attached to individual options. When this attribute is

       missing, the menu can be assumed to be ok. User agents are

       recommended to provide a cue to indicate that the menu is in

       error. 



   SRC (Source) 

       The SRC attribute is used for graphical menus to specify the URI

       for the image. Its syntax is the same as that of the HREF

       attribute of the <A> tag. 





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   MD 

       Specifies a message digest or cryptographic checksum for the

       associated image specified by the SRC attribute. It is used when

       you want to be sure that the image is indeed the same one that

       the author intended, and hasn't been modified in any way. For

       instance, MD="md5:jV2OfH+nnXHU8bnkPAad/mSQlTDZ", which specifies

       an MD5 checksum encoded as a base64 character string. The MD

       attribute is generally allowed for all elements which support

       URI based links. 



   WIDTH 

       Optional suggested width for the image. By default, this is

       given in pixels. 



   HEIGHT 

       Optional suggested height for the image. By default, this is

       given in pixels. 



   UNITS 

       This optional attribute specifies the units for the width and

       height attributes. It is one of: units=pixels (the default) or

       units=em (the width of the letter "m") which scales with the

       font size. 



   ALIGN 

       Take values TOP or MIDDLE or BOTTOM, defining whether the top or

       middle or bottom of the graphic should be aligned with the

       baseline for the text line in which the IMG element appears. 



       With ALIGN=LEFT, the graphic will float down and over to the

       current left margin, and subsequent text will wrap around the

       right hand side of the graphic. Likewise for ALIGN=RIGHT, the

       graphic aligns with the current right margin and, and text wraps

       around the left. 









































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Menu OPTIONs



   Permitted Context: SELECT

   Content Model: PCDATA 



   The OPTION element can only occur within a SELECT element. It

   represents a possible choice. It can only contain text, together

   with SGML entities for accented characters etc. 



   When the form is submitted, the NAME of the enclosing SELECT element

   is paired with the OPTION's VALUE attribute to contribute a

   name/value pair for the selection. Unselected options don't

   contribute to the form's submitted data. You can initialize the

   option to its selected state by including the SELECT attribute. 



   The SHAPE attribute is used for graphical menus to specify the

   region of the background image to be associated with this option. It

   uses the same definition as for the anchor element. 



Permitted Attributes



   ID 

       An SGML identifier used as the target for hypertext links or for

       naming particular elements in associated style sheets.

       Identifiers are NAME tokens and must be unique within the scope

       of the current document. 



   LANG 

       This is one of the ISO standard language abbreviations, e.g.

       "en.uk" for the variation of English spoken in the United

       Kingdom. It can be used by parsers to select language specific

       choices for quotation marks, ligatures and hypenation rules etc.

       The language attribute is composed from the two letter language

       code from ISO 639, optionally followed by a period and a two

       letter country code from ISO 3166. 



   CLASS 

       This a space separated list of SGML NAME tokens and is used to

       subclass tag names. By convention, the class names are

       interpreted hierarchically, with the most general class on the

       left and the most specific on the right, where classes are

       separated by a period. The CLASS attribute is most commonly used

       to attach a different style to some element, but it is

       recommended that where practical class names should be picked on

       the basis of the element's semantics, as this will permit other

       uses, such as restricting search through documents by matching

       on element class names. The conventions for choosing class names

       are outside the scope of this specification. 



   DISABLED

       When present, the option should be rendered as normal, but can't

       be modified by the user. Where practical the rendering should

       provide a cue that the option is disabled e.g. by graying out



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       the text, changing the color of the background or similar. 



   ERROR

       This attribute specifies an error message explaining why the

       option is inappropriate. When this attribute is missing, the

       option can be assumed to be ok. User agents are recommended to

       provide a cue to indicate that the option is in error. 



   VALUE

       The string to be used together with the name attribute of the

       enclosing select element, when submitting the form. It defaults

       to the content of the OPTION element. 



   SELECTED

       When present, this attribute signifies that the option should be

       initialized in its selected state. It is an error for more than

       one option to be selected for single choice menus. 



   SHAPE

       This attribute is used within menus to define shaped hotzones

       associated with this option's value. The attribute value is a

       string taking one of the following forms:

       

       



       "default" 

           Used to define a default menu choice for the menu

           background. 



       "circle x, y, r" 

           Where x and y define the center and r specifies the radius. 



       "rect x, y, w, h" 

           Where x, y define the upper left corner and w, h define the

           width and height respectively 



       "polygon x1, y1, x2, y2, ..." 

           Given n pairs of x, y coordinates, the polygon is closed by

           a line linking the n'th point to the first. Intersecting

           polygons use the non-zero winding number rule to determine

           if a point lies inside the polygon. 



       If a pointer event occurs in a region where two or more shapes

       overlap, the distance from the point to the center of gravity of

       each of the overlapping shapes is computed and the closest one

       chosen. This feature is useful when you want lots of closely

       spaced hotzones, for example over points on a map, as it allows

       you to use simple shapes without worrying about overlaps. 



       Note: The x coordinate increases to the right, and the y

       coordinate increases downwards in the same way as IMG and image

       maps. If both numbers are integers, the coordinates are

       interpreted as pixel offsets from the upper left corner of the



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       image. Otherwise, the coordinates are interpreted as scaled

       values in the range 0.0 to 1.0 across the image. Note the syntax

       is tolerant of repeated white space characters between tokens. 







































































































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Special Characters



   This section contains information of how user agents should treat

   control characters and other special characters. 



Character Data



   The characters between the tags represent text encoded according to

   ISO 8859/1 8-bit single-byte coded graphic character set known as

   Latin Alphabet No. 1, or simply Latin-1. There are 256 character

   positions in the Latin-1 encoding. Latin-1 includes characters from

   most Western European languages. It consists of the space character,

   186 characters that form a subset of the graphic characters in ISO

   6937/2 (1983), and four additional characters that are intended for

   inclusion in ISO 6937/2. For more information, see Character Sets 



   The lower 128 character positions include a space, 33 control

   characters, the 26 upper- and lowercase letters of the english

   alphabet, 10 numerals and 32 other printing characters This subset,

   functionally identical to ASCII, is defined by ISO 646 7-bit coded

   character set for information interchange, also known as the

   International Reference Version. ISO 646 is identical in most

   respect to the ANSI standard for ASCII (American Standard Code for

   Information Interchange). The only significant difference between

   ISO 646 and ASCII is the specific names assigned to the control

   characters which occupy positions 00-31 and 127 



   The upper 128 positions include a non-breaking space, a soft hyphen

   indicator, 93 graphical characters, 8 unassigned characters, and 25

   control characters. The non-breaking space and soft hyphen indicator

   are not recognized and interpreted by all HTML browsers, and their

   use is discouraged 



   There are 58 character positions which are occupied by control

   characters. See the discussion for details on the interpretation of

   control characters. Because certain special characters are subject

   to interpretation and special processing, information providers and

   browser implementors should follow these guidelines 



   Certain characters may not be accessible from your keyboard, or some

   part of your system (i.e. translation software) may not be equipped

   to deal with 8-bit character codes. HTML and many WWW browsers

   provide character entity references and numerical character

   references to facilitate the entry and interpretation of characters

   by name and by numerical position. 



   Because certain characters will be interpreted as markup, they

   should be"escaped"; that is, represented by markup -- numeric

   character or entity references. 



------------------------------------------------------------------------------

Special Characters





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   Certain characters are taken to have special meaning within the

   context of an HTML document. There are two printing characters which

   may be interpreted by the browser to have an effect of the format of

   the text: 



Space



   *   Interpreted as a word space in all contexts except <PRE>. 



   *   Interpreted as a no-break space within <PRE>. 



   The character entities &ensp; and &emsp; denote an en space and an

   em space respectively, where an en space is half the point size and

   an em space is equal to the point size of the current font. For

   fixed pitch fonts, the user agent can treat the en space as being

   equivalent to a single space character, and the em space as being

   equuivalent to two space characters. 



Non-breaking Space (&nbsp;)



   This should be treated in the same way as the space character (ASCII

   character code 32 decimal), except that the user agent should never

   break lines at this point. It is useful when you want to ensure that

   neigbouring words always stay together and don't get split across

   lines. 



Hyphen



   *   Interpreted as a hyphen glyph in all contexts. 



   *   Interpreted as a potential word space by hyphenation engine. 



   The character entities &endash; and &emdash; denote dash marks with

   the same widths as the &ensp; and &emsp; entities respectively. 



------------------------------------------------------------------------------

Control Characters



   Control characters are non-printable characters that are typically

   used for communication and device control, as format effectors, and

   as information separators. 



   In SGML applications, the use of control characters is limited in

   order to maximize the chance of sucessful interchange over

   heterogenous networks and operating systems. In HTML, there are only

   three control characters which are used. The remaining 55 control

   characters are shunned and should not appear in an HTML document.

   The valid control characters and their interpretation are: 



Horizontal Tab (HT - 9 dec) 



   *   Interpreted as a word space in all contexts except <PRE>. 





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   *   Within <PRE>, the tab should be interpreted to shift the

       horizontal column position to the next position which is a

       multiple of 8 on the same line; that is, col := (col+8) mod 8. 



Line Feed (LF - 10 dec)



   *   Interpreted as a word space in all contexts except <PRE>. 



   *   Within <PRE>, the tab should be interpreted as a shift to the

       start of a new line; that is, col := 0; row := row+1 



Carriage Return (CR - 13 dec) 



   *   Interpreted as a word space in all contexts except <PRE>. 



       



   *   Within <PRE>, the tab should be interpreted as a shift to the

       start of the line; that is, col := 0;



       



------------------------------------------------------------------------------

Numeric Character References 



   Any printing character within the 8-bit character encoding of ISO

   8859/1 (256 character positions) or the 7-bit character encoding of

   ISO 646 (128 character positions) may be represented within the text

   of an HTML document by a numeric character reference, e.g. &#233; is

   a small e with an acute accent. It is recommended that character

   entity references such as &eacute; are used in preference to

   numberic character references.  













































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Security Considerations



   Anchors, embedded images, and all other elements which contain URIs

   as parameters may cause the URI to be dereferenced. In this case,

   the security considerations of the URI specification apply. 



   Documents may be constructed whose visible contents mislead the

   reader to follow a link to unsuitable or offensive material. 



   The MD attribute is useful when authors are concerned that a linked

   object may be subsequently changed to something other than intended.

   This attribute is used to specify a cryptographic checksum for the

   linked object to provide a check on its integrity.  



















































































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<!SGML  "ISO 8879:1986"

--

        SGML Declaration for HyperText Markup Language (HTML).



--



CHARSET

         BASESET  "ISO 646:1983//CHARSET

                   International Reference Version

                   (IRV)//ESC 2/5 4/0"

         DESCSET  0   9   UNUSED

                  9   2   9

                  11  2   UNUSED

                  13  1   13

                  14  18  UNUSED

                  32  95  32

                  127 1   UNUSED

     BASESET   "ISO Registration Number 100//CHARSET

                ECMA-94 Right Part of

                Latin Alphabet Nr. 1//ESC 2/13 4/1"



         DESCSET  128  32   UNUSED

                  160  96    32



CAPACITY        SGMLREF

                TOTALCAP        200000

                GRPCAP          150000

  

SCOPE    DOCUMENT

SYNTAX   

         SHUNCHAR CONTROLS 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

                 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 127

         BASESET  "ISO 646:1983//CHARSET

                   International Reference Version

                   (IRV)//ESC 2/5 4/0"

         DESCSET  0 128 0

         FUNCTION

                  RE          13

                  RS          10

                  SPACE       32

                  TAB SEPCHAR  9

        



         NAMING   LCNMSTRT ""

                  UCNMSTRT ""

                  LCNMCHAR ".-"

                  UCNMCHAR ".-"

                  NAMECASE GENERAL YES

                           ENTITY  NO

         DELIM    GENERAL  SGMLREF

                  SHORTREF SGMLREF

         NAMES    SGMLREF

         QUANTITY SGMLREF



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                  ATTSPLEN 2100

                  LITLEN   1024

                  NAMELEN  72    -- somewhat arbitrary; taken from

                                internet line length conventions --

                  PILEN    1024

                  TAGLEN   2100

                  GRPGTCNT 150

                  GRPCNT   64                   



FEATURES

  MINIMIZE

    DATATAG  NO

    OMITTAG  YES

    RANK     NO

    SHORTTAG YES

  LINK

    SIMPLE   NO

    IMPLICIT NO

    EXPLICIT NO

  OTHER

    CONCUR   NO

    SUBDOC   NO

    FORMAL   YES

  APPINFO    "SDA"  -- conforming SGML Document Access application

                    --

>

<!-- 

        $Id: html.decl,v 1.1 1995/03/07 05:50:34 connolly Exp $



        Author: Daniel W. Connolly <connolly@hal.com>



        See also: http://www.hal.com/%7Econnolly/html-spec

          http://info.cern.ch/hypertext/WWW/MarkUp/MarkUp.html

 -->









































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Character Entity Set(s)



This section is undergoing revision ... 



   --In particular, we need to add a more complete list of character

   entities, e.g. for the characters below decimal 128 and missing

   codes such as currency signs. 



   The following entity names are used in HTML, always prefixed by

   ampersand (&) and followed by a semicolon as shown. 



   They represent particular graphic characters which have special

   meanings in places in the markup, or may not be part of the

   character set available to the writer. 



------------------------------------------------------------------------------

Numeric and Special Graphic Entities 



   The following table lists each of the supported characters specified

   in the Numeric and Special Graphic entity set, along with its name,

   syntax for use, and description. 



   This list is derived from "ISO 8879:1986//ENTITIES Numeric and

   Special Graphic//EN" however HTML does not provide support for the

   entire entity set. Only the entities listed below are supported. 



   

   Name             Syntax       Description            

   lt              &lt;        Less than sign

   gt              &gt;        Greater than sign

   amp             &amp;       Ampersand

   quot            &quot;      Double quote sign

   



------------------------------------------------------------------------------

ISO Latin 1 Character Entities 



   The following table lists each of the characters specified in the

   Added Latin 1 entity set, along with its name, syntax for use, and

   description. 



   This list is derived from "ISO 8879:1986//ENTITIES Added Latin

   1//EN", and HTML does provide support for the entire entity set. 



   

   Name            Syntax      Description            

   Aacute          &Aacute;    Capital A, acute accent

   Agrave          &Agrave;    Capital A, grave accent

   Acirc           &Acirc;     Capital A, circumflex accent

   Atilde          &Atilde;    Capital A, tilde

   Aring           &Aring;     Capital A, ring

   Auml            &Auml;      Capital A, dieresis or umlaut mark

   AElig           &AElig;     Capital AE dipthong (ligature)



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   Ccedil          &Ccedil;    Capital C, cedilla

   Eacute          &Eacute;    Capital E, acute accent

   Egrave          &Egrave;    Capital E, grave accent

   Ecirc           &Ecirc;     Capital E, circumflex accent

   Euml            &Euml;      Capital E, dieresis or umlaut mark

   Iacute          &Iacute;    Capital I, acute accent

   Igrave          &Igrave;    Capital I, grave accent

   Icirc           &Icirc;     Capital I, circumflex accent

   Iuml            &Iuml;      Capital I, dieresis or umlaut mark

   ETH             &ETH;       Capital Eth, Icelandic

   Ntilde          &Ntilde;    Capital N, tilde

   Oacute          &Oacute;    Capital O, acute accent

   Ograve          &Ograve;    Capital O, grave accent

   Ocirc           &Ocirc;     Capital O, circumflex accent

   Otilde          &Otilde;    Capital O, tilde

   Ouml            &Ouml;      Capital O, dieresis or umlaut mark

   Oslash          &Oslash;    Capital O, slash

   Uacute          &Uacute;    Capital U, acute accent

   Ugrave          &Ugrave;    Capital U, grave accent

   Ucirc           &Ucirc;     Capital U, circumflex accent

   Uuml            &Uuml;      Capital U, dieresis or umlaut mark

   Yacute          &Yacute;    Capital Y, acute accent

   

   THORN           &THORN;     Capital THORN, Icelandic

   szlig           &szlig;     Small sharp s, German (sz ligature)

   

   aacute          &aacute;    Small a, acute accent

   agrave          &agrave;    Small a, grave accent

   acirc           &acirc;     Small a, circumflex accent

   atilde          &atilde;    Small a, tilde

   atilde          &atilde;    Small a, tilde

   auml            &auml;      Small a, dieresis or umlaut mark

   aelig           &aelig;     Small ae dipthong (ligature)

   ccedil          &ccedil;    Small c, cedilla

   eacute          &eacute;    Small e, acute accent

   egrave          &egrave;    Small e, grave accent

   ecirc           &ecirc;     Small e, circumflex accent

   euml            &euml;      Small e, dieresis or umlaut mark

   iacute          &iacute;    Small i, acute accent

   igrave          &igrave;    Small i, grave accent

   icirc           &icirc;     Small i, circumflex accent

   iuml            &iuml;      Small i, dieresis or umlaut mark

   eth             &eth;       Small eth, Icelandic

   ntilde          &ntilde;    Small n, tilde

   oacute          &oacute;    Small o, acute accent

   ograve          &ograve;    Small o, grave accent

   ocirc           &ocirc;     Small o, circumflex accent

   otilde          &otilde;    Small o, tilde

   ouml            &ouml;      Small o, dieresis or umlaut mark

   oslash          &oslash;    Small o, slash

   uacute          &uacute;    Small u, acute accent

   ugrave          &ugrave;    Small u, grave accent

   ucirc           &ucirc;     Small u, circumflex accent



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   uuml            &uuml;      Small u, dieresis or umlaut mark

   yacute          &yacute;    Small y, acute accent

   thorn           &thorn;     Small thorn, Icelandic

   yuml            &yuml;      Small y, dieresis or umlaut mark

   



------------------------------------------------------------------------------

Numerical Character References 



   This list, sorted numerically, is derived from the ISO 8859/1 8-bit

   single-byte coded graphic character set: 



   

   Reference           Description

   &#00;-&#08;         Unused 

   &#09;               Horizontal tab

   &#10;               Line feed

   &#11;-&#31;         Unused

   

   &32;                Space

   &33;                Exclamation mark

   &34;                Quotation mark

   &35;                Number sign

   &36;                Dollar sign

   &37;                Percent sign

   &38;                Ampersand

   &39;                Apostrophe

   &40;                Left parenthesis

   &41;                Right parenthesis

   &42;                Asterisk

   &43;                Plus sign

   &44;                Comma

   &45;                Hyphen

   &46;                Period (fullstop)

   &47;                Solidus (slash)

   

   &#48; - &#57;       Digits 0-9

   

   &58;                Colon

   &59;                Semi-colon

   &60;                Less than

   &61;                Equals aign

   &62;                Greater than

   &63;                Question mark

   &64;                Commercial at

        

   &#65;-&#90;         Letters A-Z

   

   &91;                Left square bracket

   &92;                Reverse solidus (backslash)

   &93;                Right square bracket

   &95;                Horizontal bar

   &96;                Acute accent



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   &#97;-&#122;        Letters a-z

   

   &123;               Left curly brace

   &124;               Vertical bar

   &125;               Right curly brace

   &126;               Tilde

   

   &#127;- &#160;      Unused

   

   &161;               Inverted exclamation

   &162;               Cent sign

   &163;               Pound sterling

   &164;               General currency sign

   &165;               Yen sign

   &166;               Broken vertical bar

   &167;               Section sign

   &168;               Umlaut (dieresis)

   &169;               Copyright

   &170;               Feminine ordinal

   &171;               Left angle quote, guillemotleft

   &172;               Not sign

   &173;               Soft hyphen

   &174;               Registered trademark

   &175;               Macron accent

   &176;               Degree sign

   &177;               Plus or minus

   &178;               Superscript two

   &179;               Superscript three

   &180;               Acute accent

   &181;               Micro sign

   &182;               Paragraph sign

   &183;               Middle dot

   &184;               Cedilla

   &185;               Superscript one

   &186;               Masculine ordinal

   &187;               Right angle quote, guillemotright

   &188;               Fraction one-fourth

   &189;               Fraction one-half

   &190;               Fraction three-fourths

   &191;               Inverted question mark

   

   &192;               Capital A, acute accent

   &193;               Capital A, grave accent

   &194;               Capital A, circumflex accent

   &195;               Capital A, tilde

   &196;               Capital A, ring

   &197;               Capital A, dieresis or umlaut mark

   &198;               Capital AE dipthong (ligature)

   &199;               Capital C, cedilla

   &200;               Capital E, acute accent

   &201;               Capital E, grave accent

   &202;               Capital E, circumflex accent



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   &203;               Capital E, dieresis or umlaut mark

   &204;               Capital I, acute accent

   &205;               Capital I, grave accent

   &206;               Capital I, circumflex accent

   &207;               Capital I, dieresis or umlaut mark

   &208;               Capital Eth, Icelandic

   &209;               Capital N, tilde

   &210;               Capital O, acute accent

   &211;               Capital O, grave accent

   &212;               Capital O, circumflex accent

   &213;               Capital O, tilde

   &214;               Capital O, dieresis or umlaut mark

   

   &215;               Multiply sign

   

   &216;               Capital O, slash

   &217;               Capital U, acute accent

   &218;               Capital U, grave accent

   &219;               Capital U, circumflex accent

   &220;               Capital U, dieresis or umlaut mark

   &221;               Capital Y, acute accent

   

   &222;               Capital THORN, Icelandic

   &223;               Small sharp s, German (sz ligature)

   

   &224;               Small a, acute accent

   &225;               Small a, grave accent

   &226;               Small a, circumflex accent

   &227;               Small a, tilde

   &228;               Small a, tilde

   &229;               Small a, dieresis or umlaut mark

   &230;               Small ae dipthong (ligature)

   &231;               Small c, cedilla

   &232;               Small e, acute accent

   &233;               Small e, grave accent

   &234;               Small e, circumflex accent

   &235;               Small e, dieresis or umlaut mark

   &236;               Small i, acute accent

   &237;               Small i, grave accent

   &238;               Small i, circumflex accent

   &239;               Small i, dieresis or umlaut mark

   &240;               Small eth, Icelandic

   &241;               Small n, tilde

   &242;               Small o, acute accent

   &243;               Small o, grave accent

   &244;               Small o, circumflex accent

   &245;               Small o, tilde

   &246;               Small o, dieresis or umlaut mark

   

   &247;               Division sign

   

   &248;               Small o, slash

   &249;               Small u, acute accent



Dave Raggett                                                          Page 152



HTML 3.0                                                       28th March 1995



   &250;               Small u, grave accent

   &251;               Small u, circumflex accent

   &252;               Small u, dieresis or umlaut mark

   &253;               Small y, acute accent

   &254;               Small thorn, Icelandic

   &255;               Small y, dieresis or umlaut mark

   































































































Dave Raggett                                                          Page 153



HTML 3.0                                                       28th March 1995



Math Entities



This list is in a very preliminary stage ...



   --I hope to use ISO names where practical, and want to ensure that

   names are meaningful, rather than cryptic. The character codes for

   common fonts will be included, although which fonts to include is

   still under review.-- 



   The following sets out the range of math symbols supported by HTML

   math, giving the HTML entity name, the corresponding LaTeX command

   name and a short description. Character codes are given in

   hexadecimal when available for the Postscript symbol set and HP's

   math-8 symbol set. 



Continuation dots - ellipsis



   

   &ldots;     \ldots    three dots on the baseline

   &cdots;     \cdots    three dots on same level as a minus sign

   &vdots;     \vdots    three vertical dots

   &ddots;     \ddots    diagonal dots (top left to bottom right)

   &dotfill;   \dotfill  like cdots but fills column in an array

   



Added Spacing



   

   &thinsp;    \,        thin space

   &sp;        \:        medium space

   &emsp;      \;        thick space

   &quad;      \quad     huge space

   



Lower case Greek Letters



                                         PS-Symbol Math-8

   &alpha;     \alpha        alpha          61      61

   &beta;      \beta         beta           62      62

   &gamma;     \gamma        gamma          67      63

   &delta;     \delta        delta          64      64

   &epsilon;   \epsilon      epsilon        --      65

   &vepsilon;  \varepsilon   var epsilon    65      3B

   &zeta;      \zeta         zeta           7A      66

   &eta;       \eta          eta            68      67

   &theta;     \theta        theta          71      68

   &vtheta;    \vartheta     var theta      --      79

   &iota;      \iota         iota           69      69

   &kappa;     \kappa        kappa          6B      6A

   &lambda;    \lambda       lambda         6C      6B

   &mu;        \mu           mu             6D      6C

   &nu;        \nu           nu             6E      6D

   &xi;        \xi           xi             78      6E



Dave Raggett                                                          Page 154



HTML 3.0                                                       28th March 1995



   &omicron;   ....          omicron        6F      6F

   &pi;        \pi           pi             70      70

   &varpi;     \varpi        var pi         76      7B

   &rho;       \rho          rho            72      71

   &varrho;    \varrho       var rho        --      --

   &sigma;     \sigma        sigma          73      72

   &vsigma;    \varsigma     var sigma      56      5B

   &tau;       \tau          tau            74      73

   &upsilon;   \upsilon      upsilon        75      74

   &phi;       \phi          phi            66      75

   &varphi;    \varphi       var phi        6A      7A

   &chi;       \chi          chi            63      76

   &psi;       \psi          psi            79      77

   &omega;     \omega        omega          77      78

   



   Note: LaTeX uses the latin letter o for omicron.  











































































Dave Raggett                                                          Page 155



HTML 3.0                                                       28th March 1995



<!-- Standard ISO/WWW icons courtesy of Bert Bos and Kevin Hughes



    These can be used in place of default symbols for list items or as

    part of hypertext links, and save time needed to download images.

    Browsers can define them in terms of library images or as URL/URNs.

-->





<!ENTITY ftp SDATA "ftp" -- ftp server -->

<!ENTITY gopher SDATA "gopher" -- gopher server -->

<!ENTITY telnet SDATA "telnet" -- telnet connection -->

<!ENTITY archive SDATA "archive" -- archive server -->

<!ENTITY filing.cabinet SDATA "filing.cabinet" -- filing cabinet -->

<!ENTITY folder SDATA "folder" -- folder or directory -->

<!ENTITY fixed.disk SDATA "fixed.disk" -- fixed media drive -->

<!ENTITY disk.drive SDATA "disk.drive" -- removeable media drive -->

<!ENTITY document SDATA "document" -- unspecified document type -->

<!ENTITY unknown.document SDATA "unknown.document" -- unrecognised document type -->

<!ENTITY text.document SDATA "text.document" -- text/plain, text.html etc. -->

<!ENTITY binary.document SDATA "binary.document" -- binary data -->

<!ENTITY binhex.document SDATA "binhex.document" -- binhex format -->

<!ENTITY audio SDATA "audio" -- audio sequence -->

<!ENTITY film SDATA "film" -- film or animation, such as an MPEG movie -->

<!ENTITY image SDATA "image" -- photograph, drawing or graphic of any kind -->

<!ENTITY map SDATA "map" -- geographical or a schematic map -->

<!ENTITY form SDATA "form" -- fill-out form -->

<!ENTITY mail SDATA "mail" -- email messages -->

<!ENTITY parent SDATA "parent" -- parent of current document -->

<!ENTITY next SDATA "next" -- next document in current sequence -->

<!ENTITY previous SDATA "previous" -- previous document in current sequence -->

<!ENTITY home SDATA "home" -- home document -->

<!ENTITY toc SDATA "toc" -- table of contents -->

<!ENTITY glossary SDATA "glossary" -- glossary of terms etc. -->

<!ENTITY index SDATA "index" -- searchable index -->

<!ENTITY summary SDATA "summary" -- summary -->



<!ENTITY calculator SDATA "calculator" -- A calculator -->

<!ENTITY caution SDATA "caution" -- Warnign sign -->

<!ENTITY clock SDATA "clock" -- A clock -->

<!ENTITY compressed.document SDATA "compressed.document">

<!ENTITY diskette SDATA "diskette" -- A diskette -->

<!ENTITY display SDATA "display" -- A computer screen -->

<!ENTITY fax SDATA "fax" -- A fax machine -->

<!ENTITY mail.in SDATA "mail.in" -- mail-in tray -->

<!ENTITY mail.out SDATA "mail.out" -- mail-out tray -->

<!ENTITY mouse SDATA "mouse" -- mouse/pointing device -->

<!ENTITY printer SDATA "printer" -- hardcopy device -->

<!ENTITY tn3270 SDATA "tn3270" --tn3270 terminal session -->

<!ENTITY trash SDATA "trash" -- waste paper basket -->

<!ENTITY uuencoded.document SDATA "uuencoded.document" -- uuencoded data -->









Dave Raggett                                                          Page 156



HTML 3.0                                                       28th March 1995



<!--

        html3.dtd



        Document Type Definition for the HyperText Markup Language (HTML DTD)



        Draft: Fri 24-Mar-95 09:46:33



        Author: Dave Raggett <dsr@hplb.hpl.hp.com>



        W3O is developing a testbed browser to provide practical

        experience with HTML 3.0 before it becomes a standard.

        See:  http://www.w3.org/hypertext/WWW/Arena/



        This is an open process and comments are welcomed on the

        www-html mailing list.



        Please use the following MIME content type:

        

                Content-Type: text/html; version=3.0

                

        This will allow clients to distinguish HTML 3.0 from current

        HTML documents. This is most easily achieved by saving

        files with the extension ".html3" or ".ht3" so that servers

        can easily distinguish these files from HTML 2.0 files.

        

        The entity HTML.Recommended can be used to give a more rigorous

        version of the DTD suitable for use with SGML authoring tools.

        The default version of the DTD offers a laxer interpretation,

        e.g. allowing authors to omit leading <P> elements. You can

        switch on the more rigorous version of the DTD by including

        the following at the start of your HTML document.



         <!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 3.0//EN//"

            [ <!ENTITY % HTML.Recommended "INCLUDE"> ] >





        Design Objectives:



        o   Backwards compatibility with 2.0



        o   Tightening up HTML.Recommended and

            moving more things to HTML.Deprecated



        o   Keep HTML - simple don't compete with CALS



        o   Make it practical for people to edit HTML 3.0

            documents directly, i.e. avoid long names.



        o   Tables, figures and math from HTML+

            with tweaks based on recent experience



        o   Client-side event handling for figures

            and graphical form selection menus



Dave Raggett                                                          Page 157



HTML 3.0                                                       28th March 1995





        o   Add limited presentational controls with

            a view to use of linked style sheets

            (style overrides are supported)



        o   Compatibility with ICADD as per Yuri's suggestions



        HTML 3.0 relies on linked style info to give authors

        control over the appearence of documents. Such info is

        placed in a linked style sheet, or as overrides in the

        HTML document head, using the STYLE element. The generic

        CLASS attribute can be used to subclass elements when

        you want to use a different style from normal, e.g. you

        might use <h2 class=bigcaps> for headers with enlarged

        capital letters. Note that the class attribute has a

        wider scope than just style changes, e.g. browsers could

        provide the means for searching through documents,

        restricting search according to element class values.



        The DTD contains a small number of attributes for direct

        control of basic alignment parameters; column widths for

        tables; support for custom bullets, sequence numbering for

        lists and headers; and text flow. These attributes offer

        control over appearence which would be inconvenient to

        express exclusively via associated style sheets.



        The MD attribute for each hypertext or inline link specifies a

        message digest such as MD5 for the linked object and is needed

        to ensure someone hasn't tampered with a linked document.



  History:

  

    24th March '95

    

    Changed ROLE->CLASS for HTML element

    Added dummy elements to fix problem with mixed

    content models for BODY, BLOCKQUOTE/BQ and FIG

    Dropped audio fields from FORMs

    Reinstated MIN/MAX for range fields

    Reinstated DISABLED and ERROR attributes for fields

  

    22nd March '95

    

    Changed from em to en units. The latter

    is a typographical unit = half point size

    Merged NEEDS into CLEAR for control of textflow

  

    21st March '95

    

    Added REL=Banner to LINK element

    Added BANNER element in place of <DIV CLASS=BANNER>

    Added RANGE and SPOT elements

    Added FN in place of <NOTE ROLE=FOOTNOTE>



Dave Raggett                                                          Page 158



HTML 3.0                                                       28th March 1995



    Changed ROLE->CLASS for NOTE element



    17th March '95

    

    Fixed bug in PRE content model

    Changed external references to omit trailling //

    Dropped <!DOCTYPE HTML [ ... ]> wrapper to avoid problems

      with "real" sgml parsers

    Added NOFLOW attribute to FIG and TABLE

    Fixed typo in IMG ALIGN attribute

    Made SELECT match IMG for graphic attributes

    Added decimal alignment for tabs and table cells

    Added ALIGN attribute to TEXTAREA for parity

      with IMG and INPUT, including ALIGN=LEFT etc.

    

    13th March '95

    

    Dropped MARK tag on advice from SGML Open

    Allowed spaces in table colspec attribute

    Changed ARRAY element

    Added CHOOSE tag to BOX element

    Cleaned up PRE content model

    Obsoleted tags incompatible with SGML

    

    6th March '95

    

    Added several tags to MATH: %mathface, %mathvec

    and improved ROOT, with new SQRT convience tag

    

    1st March '95

    

    Dropped align attribute from BR element

    Added indent attribute to TAB

    Added optional CREDIT to end of BQ

    Changed FIG to %body.content to allow headers

    

    22nd February '95

    

    Added align attribute, and dropped before, after, center and right

      attributes to clean up TAB element

    Added INS and DEL for legal documents    

    Added CREDIT to end of FIG element

    Dropped FN in favor of <NOTE ROLE=FootNote>

    

    9th Feburuary '95



    Dropped base attribute mechanism for scoping relative URLs

    Dropped nofold attribute for disabling whitespace folding

    Dropped border width attributes for FIG (-> style sheet)

    Dropped delims attribute from math BOX element

    Dropped stylistic attributes from OL such as inherit (-> stylesheet)

    Added baseline to list of valign attribute values for tables.

    Added DIV element for generic container class and static banners



Dave Raggett                                                          Page 159



HTML 3.0                                                       28th March 1995



    Added MARK element for marked range class

    Added closed set of LINK REL values for toolbars

    Added numbering attributes to headers

    Added bullet attributes to headers

    Added TERM element to math for style sheet control of term rendering

    Changed to imagemap=URI for server-side event handling for FIG/OVERLAY

    Changed delimiter attributes for math arrays

    Changed ROOT element for maths to allow an arbitrary radix

    Simplified numbering attributes for ordered lists

    Simplified STYLE element to leave binding to style language

-->



<!ENTITY % HTML.Version

        "-//IETF//DTD HTML 3.0//EN"



        -- Typical usage:



            <!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 3.0//EN">

            <html>

            ...

            </html>

        --

        >



<!--================== Flags for Marked Sections ==========================-->



<!ENTITY % HTML.Recommended "IGNORE"

        -- Certain features of the language are necessary for compatibility

           with widespread usage, but they may compromise the structural

           integrity of a document. This feature test entity enables

           a more prescriptive document type definition that eliminates

           the above features.

        -->



<![ %HTML.Recommended [

        <!ENTITY % HTML.Deprecated "IGNORE">

]]>



<!ENTITY % HTML.Deprecated "INCLUDE"

        -- Certain features of the language are necessary for compatibility

           with earlier versions of the specification, but they tend

           to be used an implemented inconsistently, and their use is

           deprecated. This feature test entity enables a document type

           definition that eliminates these features.

        -->

        

<!ENTITY % HTML.Obsoleted "IGNORE"

        -- The XMP, LISTING and PLAINTEXT tags are incompatible with SGML

           and derive from very early versions of HTML. They require non-

           standard parsers and will cause problems for processing

           documents with standard SGML tools.

        -->





Dave Raggett                                                          Page 160



HTML 3.0                                                       28th March 1995



<!--================== Imported Names =====================================-->



<!ENTITY % Content-Type "CDATA"

        -- meaning a MIME content type, as per RFC1521

        -->



<!ENTITY % HTTP-Method "GET | POST"

        -- as per HTTP specification

        -->



<!ENTITY % URI "CDATA"

        -- The term URI means a CDATA attribute

           whose value is a Uniform Resource Identifier,

           as defined by

        "Uniform Resource Identifiers" by Tim Berners-Lee

        aka http://info.cern.ch/hypertext/WWW/Addressing/URL/URI_Overview.html

        aka RFC 1630



        Note that CDATA attributes are limited by the LITLEN

        capacity (1024 in the current version of html.decl),

        so that URIs in HTML have a bounded length.



        -->



<!ENTITY % REAL "CDATA" -- real numbers (not in SGML) -->



<!ENTITY % SHAPE "CDATA" 

    -- Shape of hotzone in image.



       All coordinates are assumed to be numbers in the range 0 to 1

       and interpreted as fractional width/height and measured from

       the top left corner of the associated image.



       The attribute value is a string taking one of the following forms:

       

                "default"

                

       Used to define a default link for the figure background.



            "circle x, y, r" 



       (x, y) define the center and r the radius.



            "rect x, y, w, h"



       (x, y) defines upper left, and w and h the width and height.



            "polygon x1, y1, x2, y2, ..."



       Given n pairs of x, y coordinates, the polygon is closed by a

       line linking the n'th point to the first. Intersecting polygons

       use the non-zero winding number rule to determine if a point lies

       inside the polygon.I



Dave Raggett                                                          Page 161



HTML 3.0                                                       28th March 1995



    --

>



<!-- 3.0 Parameter Entities -->



<!ENTITY % heading "H1|H2|H3|H4|H5|H6">



<![ %HTML.Obsoleted [

    <!ENTITY % preformatted "PRE | XMP | LISTING">

]]>





<![ %HTML.Deprecated [

    <!ENTITY % list "UL | OL | DIR | MENU">

    <!ENTITY % blockquote "BLOCKQUOTE | BQ">

]]>



<!ENTITY % list "UL | OL">



<!ENTITY % blockquote "BQ">



<!ENTITY % preformatted "PRE">





<!-- The CLASS attribute is used to subclass HTML elements for

     rendering purposes, when used with style sheets, e.g. DSSSL lite -->



<!ENTITY % attrs  -- common attributes for elements --

        'id       ID      #IMPLIED -- as target for hrefs (link ends) --

         lang     CDATA   "en.us"  -- ISO language, country code --

         class    NAMES   #IMPLIED -- for subclassing elements --'>



<!-- SGML standard forces different NAMES for all attribute values

     in the same element, regardless of the attribute name! As a result

     CDATA is used for CLEAR attribute to avoid clash with ALIGN attribute.-->



<!--

When text flows around a figure or table in the margin, you sometimes want

to start an element like a header, paragraph or list below the figure rather

than alongside it. The CLEAR attribute allows you to move down unconditionally:



        clear=left          move down until left margin is clear

        clear=right         move down until right margin is clear

        clear=all           move down until both margins are clear



Alternatively, you can decide to place the element alongside the figure just

so long as there is enough room. The minimum width needed is specified as:



        clear="40 en"       move down until there is at least 40 en units free

        clear="100 pixels"  move down until there is at least 100 pixels free

        

The style sheet (or browser defaults) may provide default minimum widths for

each class of block-like elements.



Dave Raggett                                                          Page 162



HTML 3.0                                                       28th March 1995



-->



<!ENTITY % needs -- Attributes for controlling text flow. Used in headers

                    and other elements to guarantee sufficient room --

        'clear  CDATA #IMPLIED'>



<!--

    The following attribute may be included where ever a URL can be given:



    md      message digest e.g. md="md5:jV2OfH+nnXHU8bnkPAad/mSQlTDZ"

            where the digest is base64 encoded and preceded by a prefix

            denoting the algorithm (in this case MD5).

-->



<!ENTITY % url.link -- Attributes associated with URL based links --

        "md     CDATA  #IMPLIED  -- message digest for linked object --">



<!--================ Character mnemonic entities ==========================-->



<!-- The HTML list of Latin-1 entities includes the full range

     of characters in widely available Latin-1 fonts, and as such

     is a mixture of ISOlat1 and other ISO publishing symbols -->



<!ENTITY % HTMLlat1 PUBLIC

  "-//IETF//ENTITIES Added Latin 1 for HTML//EN">

%HTMLlat1;



<!--================ Entities for special symbols =========================-->



<!ENTITY emsp   SDATA "[emsp  ]" -- em space -->

<!ENTITY ensp   SDATA "[ensp  ]" -- en space (1/2-em) -->

<!ENTITY mdash  SDATA "[ndash ]" -- em dash -->

<!ENTITY ndash  SDATA "[ndash ]" -- en dash (1/2-em) -->

<!ENTITY nbsp   SDATA "[nbsp  ]" -- non breaking space -->

<!ENTITY shy    SDATA "[shy   ]" -- soft hyphen -->

<!ENTITY copy   SDATA "[copy  ]" -- copyright sign -->

<!ENTITY trade  SDATA "[trade ]" -- trade mark sign -->

<!ENTITY reg    SDATA "[reg   ]" -- registered sign -->



<!--================ Entities for standard icons ==========================-->



<!-- a range of standard icons such as &folder; for use

     in speeding up display of directory listings etc. -->



<!ENTITY % HTMLicons PUBLIC

  "-//IETF//ENTITIES icons for HTML//EN">

%HTMLicons;



<!--================ Entities for math symbols ============================-->



<!-- ISO subset chosen for use with the widely available Adobe math font -->



<!ENTITY % HTMLmath PUBLIC



Dave Raggett                                                          Page 163



HTML 3.0                                                       28th March 1995



  "-//IETF//ENTITIES Math and Greek for HTML//EN">

%HTMLmath;



<!--=================== Text Markup =======================================-->



<!ENTITY % font " U | S | TT | I | BIG | SMALL">



<!ENTITY % phrase "EM | STRONG | CODE | SAMP | KBD | VAR | CITE">



<!ENTITY % misc "Q | LANG | AU | DFN | PERSON | ACRONYM | ABBREV | INS | DEL">



<!ENTITY % special "TAB | MATH | A | IMG | BR">



<!ENTITY % notmath "%font | %phrase | %special | %misc">



<!ENTITY % text "#PCDATA | SUB | SUP | B | %notmath">





<!ENTITY % pre.exclusion "TAB|MATH|IMG|BIG|SMALL|SUB|SUP">



<!ELEMENT (%font|B|%phrase|%misc) - - (%text)+>

<!ATTLIST (%font|B|%phrase|%misc) %attrs;>



<!-- Subscripts and superscripts. The ALIGN attribute is only used for math -->



<!ELEMENT (SUB|SUP) - - (%text)+>

<!ATTLIST (SUB|SUP)

        %attrs;

        align (left|center|right) #IMPLIED

        >



<!-- Forced line break -->



<!ELEMENT BR    - O EMPTY>

<!ATTLIST BR

        %attrs;

        %needs; -- for control of text flow --

        >



<!-- Named left, center and right tab stops (independent of '\t' char) -->



<!ELEMENT TAB - O EMPTY>

<!ATTLIST TAB

        id       ID       #IMPLIED  -- defines named tab stop --

        indent   NUMBER   0         -- en units before new tab stop --

        to       IDREF    #IMPLIED  -- jump to named tab stop --

        align   (left|center|right|decimal) left

        dp      CDATA     #IMPLIED  -- decimal point e.g. dp="," --

        >



<!--================== Link Markup ========================================-->



<!--



Dave Raggett                                                          Page 164



HTML 3.0                                                       28th March 1995



     With HTML 3.0 you can use ID attributes on most elements for named

     link ends. The use of the NAME attribute on anchors is deprecated.



     Do we want to support arbitrary elements for link starts? This would

     involve adding HREF and related attributes to most elements.

-->



<![ %HTML.Deprecated [

    <!ENTITY % linkName "name CDATA #IMPLIED -- named link end --">

]]>



<!ENTITY % linkName "">





<!ENTITY % ToolBar "home|toc|index|glossary|copyright|

                    up|previous|next|help|bookmark"



        -- LINK RELationship values which are used to create toolbar

           buttons or menu items for navigation, where toc stands

           for table of contents and bookmark provides for an open

           ended set of links, i.e. you can use multiple bookmarks

           for key entry points. Use the optional TITLE attribute

           to override default names.

        -->



<!ENTITY % linkType "NAME"

        -- A definitive list will be specified at a later date.



           They are used



                a) by stylesheets to control how collections of

                   html nodes are rendered into printed documents



                b) for document specific toolbars/menus when used

                   with the LINK element in document head:



                    "home|toc|index|glossary|copyright|

                           up|previous|next|help|bookmark"



                   where toc stands for table of contents and

                   bookmark provides for an open ended set of links,

                   i.e. you can use several bookmarks for key entry

                   points. Use the optional TITLE attribute to

                   override default names.



                c) for hypertext paths or guided tours,

                   with REL=NODE and REL=PATH. 



                d) to make a link to a style sheet, e.g. rel=stylesheet

                   (used only with the LINK element).

                   

                e) to make a link to a separate banner, e.g. rel=banner

                   (used only with the LINK element).



Dave Raggett                                                          Page 165



HTML 3.0                                                       28th March 1995



        -->





<!ENTITY % linkExtraAttributes -- URN moved to %url.link --

       "rel %linkType #IMPLIED -- forward relationship type --

        rev %linkType #IMPLIED -- reversed relationship type

                                  to referent data --

        title   CDATA #IMPLIED -- advisory only --

        methods NAMES #IMPLIED -- supported public methods of the object:

                                        TEXTSEARCH, GET, HEAD, ... --

        ">



<![ %HTML.Deprecated [

    <!ENTITY % A.content "(%heading|%text)+">

]]>



<!ENTITY % A.content   "(%text)+">



<!ELEMENT A     - - %A.content -(A)>



<!ATTLIST A

        %attrs;

        href   %URI;  #IMPLIED

        %url.link;    -- standard link attributes --

        %linkName;     -- name attribute is deprecated; use ID instead --

        shape %SHAPE; #IMPLIED -- for shaped hotzones in FIGs --

        %linkExtraAttributes;

        >



<!--=================== Images ============================================-->



<!-- Desired widths are used for negotiating image size

     with the module responsible for painting the image.

     align=left or right cause image to float to margin

     and for subsequent text to wrap around image -->



<!ELEMENT IMG    - O EMPTY --  Embedded image -->

<!ATTLIST IMG

        %attrs;

        src  %URI;  #REQUIRED  -- URI of image to embed --

        %url.link;             -- standard link attributes --

        alt CDATA   #IMPLIED   -- for display in place of image --

        align  (top|middle|bottom|left|right) top -- relative to baseline

        --         width  NUMBER #IMPLIED -- desired width in en's or pixels --

        height NUMBER #IMPLIED -- desired height in en's or pixels --

        units  (en|pixels) pixels -- units for width and height --

        ismap (ismap) #IMPLIED -- pass clicks to server --

        >



<!--=================== Paragraphs=========================================-->



<!ELEMENT P     - O (%text)+>

<!ATTLIST P



Dave Raggett                                                          Page 166



HTML 3.0                                                       28th March 1995



        %attrs;

        align  (left|center|right|justify) #IMPLIED

        %needs; -- for control of text flow --

        nowrap (nowrap) #IMPLIED -- disable wordwrap --

        >



<!--=================== Headings, Titles, Sections ========================-->



<!ELEMENT HR    - O EMPTY -- customizable horizontal rule -->

<!ATTLIST HR

        %attrs;

        src     %URI;   #IMPLIED -- URI of custom rule graphic --

        %url.link;               -- standard link attributes --

        %needs; -- for control of text flow --

        >



<!--

  Headers can be numbered, although this is a matter for style sheets.

  The style sheet controls the numbering style:



     a) whether the parent numbering is inherited, e.g.  5.i.c

        where 5 is the current sequence number for H1 headers, and

        1 is the number for H2 headers and 3 for H3 headers.



     b) what style is used for current sequence number

        e.g. arabic, upperalpha, loweralpha, upperroman, lowerroman

        or a numbering scheme appropriate for the current language



  The skip attribute is used to skip over sequence numbers for items

  which have been left out of the list, e.g. skip=3 advances the

  sequence number past 3 omitted items. The seqnum sets the sequence

  number to a specified value. Note that the style sheet may take

  advantage of the sequence number for higher level headers.



  The dingbat or src attributes may be used to specify a bullet like

  image to be placed adjacent to the header. Defining this in the

  header element simplifies the document markup and avoids the need

  to use the clear or needs attribute in the following element to

  prevent it flowing around this image.

-->



<!ELEMENT ( %heading )  - -  (%text;)+>

<!ATTLIST ( %heading )

        %attrs;

        align  (left|center|right|justify) #IMPLIED

        %needs; -- for control of text flow --

        seqnum   NUMBER   #IMPLIED  -- starting sequence number --

        skip     NUMBER   0         -- skip seq nums for missing items --

        dingbat  ENTITY   #IMPLIED  -- dingbat entity from HTMLicons --

        src      (%URI;)  #IMPLIED  -- bullet defined by graphic --

        %url.link;                  -- standard link attributes --

        nowrap   (nowrap)  #IMPLIED -- disable wordwrap --

        >



Dave Raggett                                                          Page 167



HTML 3.0                                                       28th March 1995





<!ELEMENT TITLE - -  (#PCDATA)

          -- The TITLE element is not considered part of the flow of text.

             It should be displayed, for example as the page header or

             window title.

          -->



<!--=================== Text Flows ========================================-->



<!ENTITY % block

     "P | %list | DL

        | %preformatted

        | %blockquote

        | FORM | ISINDEX | FN

        | TABLE | FIG | NOTE">



<!--

  ((%block)* | (%text)*) would be much nicer as it would avoid the need

  for a <P> tag when all you want is a few words of text. The problem

  is that it also prevents: "<LI> <P>some text" since it forbids PCDATA

  and hence the white space between the <LI> and the <P>.

-->



<![ %HTML.Recommended [

    <!ENTITY % flow "(%block)*">

]]>



<!ENTITY % flow "(%text | %block)*">



<!ELEMENT PRE - - (%text)* -(%pre.exclusion)>



<!ATTLIST PRE

        %attrs;

        width NUMBER #implied

        %needs; -- for control of text flow --

        >



<![ %HTML.Obsoleted [



<!ENTITY % literal "CDATA"

        -- special non-conforming parsing mode where

           the only markup signal is the end tag

           in full. This will cause problems for

           standard SGML tools!

        -->



<!ELEMENT XMP - -  %literal>

<!ELEMENT LISTING - -  %literal>

<!ELEMENT PLAINTEXT - O %literal>



]]>



<!--=================== Lists =============================================-->



Dave Raggett                                                          Page 168



HTML 3.0                                                       28th March 1995





<!ELEMENT DL    - -  (LH?, (DT|DD)+) -- this is perhaps too lax? -->

<!ATTLIST DL

        %attrs;

        %needs; -- for control of text flow --

        compact (compact) #IMPLIED -- more compact style --

        >



<!ELEMENT DT    - O  (%text)+>

<!ELEMENT DD    - O  %flow;>

<!ATTLIST (DT|DD)

        %attrs;

        %needs; -- for control of text flow --

        >





<!ELEMENT (OL|UL) - -  (LH?, LI+) -- should we allow a list header ? -->



<!-- style sheet controls numbering style

    a) whether the parent numbering is inherited, e.g.  5.1.c

    b) what style is used for current sequence number

        e.g. arabic, upperalpha, loweralpha, upperroman, lowerroman

        or a numbering scheme for the current language

-->

<!ATTLIST OL

        %attrs;

        %needs; -- for control of text flow --

        continue (continue)  #IMPLIED   -- don't restart sequence number --

        seqnum    NUMBER     #IMPLIED   -- starting sequence number --

        compact (compact)    #IMPLIED   -- reduced interitem spacing --

        >



<!-- Unordered lists:



    o   single or multicolumn with

        horizontal or vertical wrapping



    o   plain or bulletted list items



    o   bullets can be customised via:

            - entities (dingbats in HTMLicons)

            - external graphic via URL

            - individual attributes on LI tags

-->

<!ATTLIST UL

        %attrs;

        %needs; -- for control of text flow --

        wrap (vert|horiz|none) none -- multicolumn list style --

        plain   (plain)  #IMPLIED   -- suppress bullets --

        dingbat  ENTITY  #IMPLIED   -- dingbat entity from HTMLicons --

        src     (%URI;)  #IMPLIED   -- bullet defined by graphic --

        %url.link;                  -- standard link attributes --

        compact (compact) #IMPLIED  -- reduced interitem spacing --



Dave Raggett                                                          Page 169



HTML 3.0                                                       28th March 1995



        >



<!ELEMENT LH - O (%text;)+ -- list header -->

<!ATTLIST LH %attrs;>



<!--

    For unordered lists, you can override the standard bullet with

    a custom graphic specified via a URI e.g. src="splash.gif" or

    a reference to one of the HTMLicons graphics e.g. dingbat=folder



    The skip attribute is used with ordered lists to skip over sequence

    numbers for items which have been left out of the list, e.g. skip=3

    advances the sequence number past 3 omitted items.

-->



<!ELEMENT LI - O %flow; -- list item -->

<!ATTLIST LI

        %attrs;

        %needs; -- for control of text flow --

        dingbat ENTITY #IMPLIED -- dingbat entity from HTMLicons --

        src  (%URI;) #IMPLIED   -- custom bullet graphic --

        %url.link;              -- standard link attributes --

        skip NUMBER 0           -- skip seq nums for missing items --

        >



<!-- DIR and MENU are now subsumed by UL with type=plain. Use the

     wrap attribute to control wrapping style for multicolumn lists -->



<![ %HTML.Deprecated [

    <!ELEMENT (DIR|MENU) - - (LI)+ -(%block)>

    <!ATTLIST (DIR|MENU)

        compact (compact) #IMPLIED>

]]>



<!--=================== Document Body =====================================-->



<![ %HTML.Recommended [

        <!ENTITY % body.content "(DIV|%heading|%block|HR|ADDRESS)*"

        -- <h1>Heading</h1>

           <p>Text ...

                is preferred to

           <h1>Heading</h1>

           Text ...

        -->

]]>



<!ENTITY % body.content "(DIV | %heading | %text | %block | HR | ADDRESS)*">



<!ELEMENT BODY O O  (BANNER?, BODYTEXT) +(SPOT)>

<!ATTLIST BODY

        %attrs;

        background %URI; #IMPLIED  -- texture tile for document background --

        >



Dave Raggett                                                          Page 170



HTML 3.0                                                       28th March 1995





<!ELEMENT BODYTEXT O O %body.content -- dummy element -->



<!-- 

  The BANNER element is used for a banner section which appears at

  the top of the window and doesn't scroll with window contents.

  This can be used for corporate logos, copyright statements and

  disclaimers, as well as customized navigation/search controls.

-->

<!ELEMENT BANNER - - %body.content>

<!ATTLIST BANNER %attrs; >



<!-- SPOT is used to insert IDs at arbitrary places

     e.g. for end points of a marked range (see RANGE) -->

<!ELEMENT SPOT - O EMPTY>

<!ATTLIST SPOT id ID #REQUIRED>



<!ELEMENT (%blockquote) - - (BODYTEXT, CREDIT?)>

<!ATTLIST (%blockquote)

        %attrs;

        %needs; -- for control of text flow --

        nowrap   (nowrap)  #IMPLIED -- disable wordwrap --

        >



<!ENTITY % address.content "((%text;)* | P*)">



<!ELEMENT ADDRESS - - %address.content>

<!ATTLIST ADDRESS

        %attrs;

        %needs; -- for control of text flow --

        >

        

<!--

  DIV can be used with the CLASS attribute to represent different

  kinds of container, e.g. chapter, section, abstract, appendix.

-->



<!ELEMENT DIV - - %body.content>

<!ATTLIST DIV

        %attrs;

        %needs; -- for control of text flow --

        align   (left|center|right) left -- alignment of following text --

        nowrap   (nowrap)  #IMPLIED -- disable wordwrap --

        >



<!--================ Forms ===============================================-->



<!--

    As HTML 2.0 plus a few extensions:



        a)  A RANGE control which varies between pair of values

            specified with the size attribute, e.g. SIZE="1, 10"





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HTML 3.0                                                       28th March 1995



        b)  FILE widget for uploading one or more files to a server



        c)  SCRIBBLE on image widget that sends the "ink" to the server



        d)  SUBMIT/RESET buttons can now be customised with an image.

            This subsumes the IMAGE type which is now deprecated.



        e)  Graphical SELECTion menus are now supported, using

            the new SHAPE attribute on OPTION elements.



    Further extensions are in the pipeline (e.g. table entry,

    multiple data formats for textarea fields and client-side

    scripts with custom widgets) but will have to wait until

    the backlog of implementation work diminishes.

-->



<!ELEMENT FORM - - %body.content -(FORM) +(INPUT|SELECT|TEXTAREA)>

<!ATTLIST FORM

        action %URI #REQUIRED -- server-side form handler --

        method (%HTTP-Method) GET -- see HTTP specification --

        enctype %Content-Type; "application/x-www-form-urlencoded"

        script %URI #IMPLIED -- link to client-side script --

        >



<![ %HTML.Deprecated [

    <!ENTITY % InputType "(TEXT | PASSWORD | CHECKBOX | RADIO | SUBMIT

                   | RESET | RANGE | FILE | SCRIBBLE | HIDDEN | IMAGE)">

]]>



<!ENTITY % InputType "(TEXT | PASSWORD | CHECKBOX | RADIO | SUBMIT

                   | RESET | RANGE | FILE | SCRIBBLE | HIDDEN)">



<!ELEMENT INPUT - O EMPTY>

<!ATTLIST INPUT

        %attrs;

        type %InputType TEXT

        name  NAME  #IMPLIED       -- required for all but submit and reset --         

        value CDATA #IMPLIED       -- required for radio buttons & checkboxes --

        disabled (disabled) #IMPLIED -- read-only fields --

        error CDATA #IMPLIED       -- why field is in error --

        checked (checked) #IMPLIED -- for radio buttons and check boxes --

        size NUMBER #IMPLIED       -- visible width of TEXT fields --

        maxlength NUMBER #IMPLIED  -- max number of chars for TEXT fields --

        min %REAL #IMPLIED         -- lower limit for RANGE fields --

        max %REAL #IMPLIED         -- upper limit for RANGE fields --

        accept CDATA #IMPLIED      -- list of MIME types for file fields --

        src   %URI  #IMPLIED       -- for fields with background images --

        %url.link;                 -- standard link attributes --

        align  (top|middle|bottom|left|right) top

        >



<!--

  SRC attribute added for graphical selection menus



Dave Raggett                                                          Page 172



HTML 3.0                                                       28th March 1995



  The WIDTH, HEIGHT and UNITS attributes apply to the

  image specified by the SRC attribute.

 -->



<!ELEMENT SELECT - - (OPTION+) -(INPUT|TEXTAREA|SELECT)>

<!ATTLIST SELECT

        %attrs;

        name CDATA #REQUIRED

        multiple (multiple) #IMPLIED

        disabled (disabled) #IMPLIED -- read-only menu --

        error CDATA #IMPLIED   -- why selections are in error --

        src  %URI  #IMPLIED    -- for graphical selection menus --

        %url.link;             -- standard link attributes --

        width  NUMBER #IMPLIED -- desired width of in en's or pixels --

        height NUMBER #IMPLIED -- desired height in en's or pixels --

        units  (en|pixels) pixels -- units for width and height --

        align  (top|middle|bottom|left|right) top

        >



<!ELEMENT OPTION - O (#PCDATA)>

<!ATTLIST OPTION

        %attrs;

        selected (selected) #IMPLIED

        value  CDATA  #IMPLIED -- default to element content --

        shape %SHAPE; #IMPLIED -- for graphical selection menus --

        disabled (disabled) #IMPLIED -- unselectable option --

        error CDATA #IMPLIED   -- why this choice is in error --

        >



<!--

  Multi-line text input field. align=left or right

  causes the field to float to margin and for

  subsequent text to wrap around the field.

-->

     

<!ELEMENT TEXTAREA - - (#PCDATA) -(INPUT|TEXTAREA|SELECT)>

<!ATTLIST TEXTAREA

        %attrs;

        name CDATA #REQUIRED

        rows NUMBER #REQUIRED

        cols NUMBER #REQUIRED

        disabled (disabled) #IMPLIED -- read-only field --

        error CDATA #IMPLIED         -- why field is in error --

        align  (top|middle|bottom|left|right) top

        >



<!--======================= Captions ======================================-->



<!ELEMENT CAPTION - - (%text;)+ -- table or figure caption -->

<!ATTLIST CAPTION

        %attrs;

        align (top|bottom|left|right) #IMPLIED

        >



Dave Raggett                                                          Page 173



HTML 3.0                                                       28th March 1995



<!--======================= Tables ========================================-->



<!--

    Tables and figures can be aligned in several ways:



    bleedleft   flush left with the left (window) border

    left        flush left with the left text margin

    center      centered (text flow is disabled for this mode)

    right       flush right with the right text margin

    bleedright  flush right with the right (window) border

    justify     when applicable the table/figure should stretch

                to fill space between the text margins



    Note: text will flow around the table or figure if the browser

    judges there is enough room and the alignment is not centered

    or justified. The table or figure may itself be part of the

    text flow around some earlier figure. You can in this case use

    the clear or needs attributes to move the new table or figure

    down the page beyond the obstructing earlier figure. Similarly,

    you can use the clear or needs attributes with other elements

    such as headers and lists to move them further down the page.

-->



<!ENTITY % block.align

        "align  (bleedleft|left|center|right|bleedright|justify) center">



<!--

    The HTML 3.0 table model has been chosen for its simplicity

    and the ease in writing filters from common DTP packages.



    By default the table is automatically sized according to the

    cell contents and the current window size. Specifying the columns

    widths using the colspec attribute allows browsers to start

    displaying the table without having to wait for last row.



    The colspec attribute is a list of column widths and alignment

    specifications. The columns are listed from left to right with

    a capital letter followed by a number, e.g. COLSPEC="L20 C8 L40".

    The letter is L for left, C for center, R for right alignment of

    cell contents. J is for justification, when feasible, otherwise

    this is treated in the same way as L for left alignment.

    Column entries are delimited by one or more space characters.

    

    The number specifies the width in en's, pixels or as a

    fractional value of the table width, as according to the

    associated units attribute. This approach is more compact

    than used with most SGML table models and chosen to simplify

    hand entry. The width attribute allows you to specify the

    width of the table in pixels, en units or as a percentage

    of the space between the current left and right margins.



    To assist with rendering to speech, row and column headers

    can be given short names using the AXIS attribute. The AXES



Dave Raggett                                                          Page 174



HTML 3.0                                                       28th March 1995



    attribute is used to explicitly specify the row and column

    names for use with each cell. Otherwise browsers can follow

    up columns and left along rows (right for some languages)

    to find the corresponding header cells.



    Table content model: Braille limits the width of tables,

    placing severe limits on column widths. User agents need

    to render big cells by moving the content to a note placed

    before the table. The cell is then rendered as a link to

    the corresponding note.



    To assist with formatting tables to paged media, authors

    can differentiate leading and trailing rows that are to

    be duplicated when splitting tables across page boundaries.

    The recommended way is to subclass rows with the CLASS attribute

    For example: <TR CLASS=Header>, <TR CLASS=Footer> are used for

    header and footer rows. Paged browsers insert footer rows at

    the bottom of the current page and header rows at the top of

    the new page, followed by the remaining body rows.

-->



<!ELEMENT TABLE - - (CAPTION?, TR*) -- mixed headers and data -->

<!ATTLIST TABLE

        %attrs;

        %needs; -- for control of text flow --

        border (border) #IMPLIED -- draw borders --

        colspec CDATA   #IMPLIED -- column widths and alignment --

        units  (en|pixels|relative) en -- units for column widths --

        dp      CDATA   #IMPLIED -- decimal point e.g. dp="," --

        width NUMBER    #IMPLIED -- absolute or percentage width --

        %block.align;  -- horizontal alignment --

        noflow (noflow) #IMPLIED -- noflow around table --

        nowrap (nowrap) #IMPLIED -- don't wrap words --

        >



<!ENTITY % cell "TH | TD">

<!ENTITY % horiz.align "left|center|right|justify">

<!ENTITY % vert.align  "top|middle|bottom|baseline">



<!--

    Browsers should tolerate an omission of the first <TR>

    tag as it is implied by the context. Missing trailing

    <TR>s implied by rowspans should be ignored.



    The alignment attributes act as defaults for rows

    overriding the colspec attribute and being in turn

    overridden by alignment attributes on cell elements.

    Use valign=baseline when you want to ensure that text

    in different cells on the same row is aligned on the

    same baseline regardless of fonts. It only applies

    when the cells contain a single line of text.

-->





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HTML 3.0                                                       28th March 1995



<!ELEMENT TR - O (%cell)* -- row container -->

<!ATTLIST TR

        %attrs;

        align  (%horiz.align) #IMPLIED -- horizontal alignment --

        valign (%vert.align)  top  -- vertical alignment --

        dp     CDATA     #IMPLIED  -- decimal point e.g. dp="," --

        nowrap (nowrap)  #IMPLIED  -- don't wrap words --

        >



<!--

    Note that table cells can include nested tables.

    Missing cells are considered to be empty, while

    missing rows should be ignored, i.e. if a cell

    spans a row and there are no further TR elements

    then the implied row should be ignored.

-->



<!ELEMENT (%cell) - O %body.content>

<!ATTLIST (%cell)

        %attrs;

        colspan NUMBER    1      -- columns spanned --

        rowspan NUMBER    1      -- rows spanned --

        align  (%horiz.align) #IMPLIED -- horizontal alignment --

        valign (%vert.align) top -- vertical alignment --

        dp      CDATA    #IMPLIED  -- decimal point e.g. dp="," --

        nowrap (nowrap)  #IMPLIED  -- don't wrap words --

        axis CDATA #IMPLIED -- axis name, defaults to element content --

        axes CDATA #IMPLIED -- comma separated list of axis names --

        >



<!--====================== Figures ========================================-->



<!--

  The element contains text for use in non-graphical displays. Note that

  you can use the shape attribute in anchors to specify hotzones on images.

  This provides for local processing of pointer clicks and a unified method

  for dealing with graphical and non-graphical displays.



  Text is flowed around figures when the figure is left or right aligned.

  You can request the browser to move down until there is enough room for

  the next element, see the CLEAR and NEED attributes (in %needs)



  Figures offer a path towards embedding arbitrary information formats

  via some kind of OLE/OpenDoc mechanism.

-->



<!ELEMENT FIG - - (OVERLAY*, CAPTION?, FIGTEXT, CREDIT?) -(FIG|IMG)>

<!ATTLIST FIG

        %attrs;

        %needs;                  -- for control of text flow --

        src  %URI;  #REQUIRED    -- URI of document to embed --

        %url.link;               -- standard link attributes --

        %block.align;            -- horizontal alignment --



Dave Raggett                                                          Page 176



HTML 3.0                                                       28th March 1995



        noflow (noflow) #IMPLIED -- noflow around figure --

        width  NUMBER #IMPLIED   -- desired width in units --

        height NUMBER #IMPLIED   -- desired height in units --

        units (en|pixels) pixels -- specifies units as en's or pixels --

        imagemap (%URI) #IMPLIED -- pass background clicks to server --

        >

        

<!ELEMENT FIGTEXT O O %body.content -- dummy element -->



<!--

    Figure overlays. When combined with local caching, overlays

    provide a cheap way of modifying a larger base image sent as

    part of a previous page.

-->



<!ELEMENT OVERLAY - O EMPTY -- image overlay -->

<!ATTLIST OVERLAY

        src  %URI;  #REQUIRED    -- URI of image overlay --

        %url.link;               -- standard link attributes --

        units (en|pixels) pixels -- specifies units as en's or pixels --

        x      NUMBER   0        -- offset from left in units --

        y      NUMBER   0        -- offset from top in units --

        width  NUMBER #IMPLIED   -- desired width in units --

        height NUMBER #IMPLIED   -- desired height in units --

        imagemap (%URI) #IMPLIED -- pass background clicks to server --

        >



<!ELEMENT CREDIT - - (%text;)* -- source of image -->

<!ATTLIST CREDIT

        %attrs;

        >



<!--======================== Notes ========================================-->



<!--

The NOTE element is used for admonishments. The CLASS attribute

is used to differentiate NOTE's, e.g. Note, Caution or Warning.

-->



<!ELEMENT NOTE - - %body.content; -- admonishment -->

<!ATTLIST NOTE

        %attrs;

        src %URI;   #IMPLIED  -- URI of custom graphic --

        %url.link;            -- standard link attributes --

        %needs; -- for control of text flow --

        >



<!--======================== Footnotes ====================================-->



<!--

Typically rendered as popup note. These elements are referenced

by hypertext links specified with the anchor element.

-->



Dave Raggett                                                          Page 177



HTML 3.0                                                       28th March 1995



<!ELEMENT FN - - %body.content;>

<!ATTLIST FN %attrs;>



<!--======================== Math  ========================================-->



<!-- Use &thinsp; &emsp; etc for greater control of spacing. -->



<!-- Subscripts and Superscripts



  <SUB> and <SUP> are used for subscripts and superscripts.



                                          i j

      X <SUP>i</SUP>Y<SUP>j</SUP>  is   X  Y



  i.e. the space following the X disambiguates the binding.

  The align attribute can be used for horizontal alignment,

  e.g. to explicitly place an index above an element:

                                              i

        X<sup align=center>i</sup>  produces  X



Short references are defined for superscripts, subscripts and boxes

to save typing when manually editing HTML math, e.g.



      x^2^    is mapped to   x<sup>2</sup>

      y_z_    is mapped to   y<sub>z</sub>

      {a+b}   is mapped to   <box>a + b</box>



Note that these only apply within the MATH element and can't be

used in normal text!

-->

<!ENTITY REF1   STARTTAG   "SUP">

<!ENTITY REF2   ENDTAG     "SUP">

<!ENTITY REF3   STARTTAG   "SUB">

<!ENTITY REF4   ENDTAG     "SUB">

<!ENTITY REF5   STARTTAG   "BOX">

<!ENTITY REF6   ENDTAG     "BOX">



<!USEMAP MAP1   MATH>

<!USEMAP MAP2   SUP>

<!USEMAP MAP3   SUB>

<!USEMAP MAP4   BOX>



<!SHORTREF MAP1 "^" REF1

                "_" REF3

                "{" REF5 >



<!SHORTREF MAP2 "^" REF2

                "_" REF3

                "{" REF5 >



<!SHORTREF MAP3 "_" REF4

                "^" REF1

                "{" REF5 >



Dave Raggett                                                          Page 178



HTML 3.0                                                       28th March 1995





<!SHORTREF MAP4 "}" REF6

                "^" REF1

                "_" REF3

                "{" REF5 >



<!--

 The inclusion of %math and exclusion of %notmath is used here

 to alter the content model for the B, SUB and SUP elements,

 to limit them to formulae rather than general text elements.

-->



<!ENTITY % mathvec "VEC|BAR|DOT|DDOT|HAT|TILDE" -- common accents -->

<!ENTITY % mathface "B|T|BT" -- control of font face -->

<!ENTITY % math "BOX|ABOVE|BELOW|%mathvec|ROOT|SQRT|ARRAY|SUB|SUP|%mathface">

<!ENTITY % formula "#PCDATA|%math">



<!ELEMENT MATH - - (#PCDATA)* -(%notmath) +(%math)>

<!ATTLIST MATH

        id      ID      #IMPLIED

        class    NAMES   #IMPLIED -- e.g. class=chem -->



<!-- The BOX element acts as brackets. Delimiters are optional and

     stretch to match the height of the box. The OVER element is used

     when you want a line between numerator and denominator. This line

     is suppressed with the alternative ATOP element. CHOOSE acts like

     ATOP but adds enclosing round brackets as a convenience for binomial

     coefficients. Note the use of { and } as shorthand for <BOX> and

     </BOX> respectively:



                           1 + X

     {1 + X<OVER>Y}  is   _______

                             Y



                                 a + b

     {a + b<ATOP>c - d} is  

                                 c - d



     The delimiters are represented using the LEFT and RIGHT

     elements as in:



     {[<LEFT>x + y<RIGHT>]}   is   [ x + y ]

     {(<LEFT>a<RIGHT>]}       is   (a]

     {||<LEFT>a<RIGHT>||}     is   || a ||



     Use &lbrace; and &rbrace; for "{" and "}" respectively as

     these symbols are used as shorthand for BOX, e.g.



     {&lbrace;<LEFT>a+b<RIGHT>&rbrace;}  is  {a+b}



     You can stretch definite integrals to match the integrand, e.g.



     {&int;<SUB>a</SUB><SUP>b</SUP><LEFT>{f(x)<over>1+x} dx}



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HTML 3.0                                                       28th March 1995





            b

            /  f(x)

            | ----- dx

            / 1 + x

            a



     Note the complex content model for BOX is a work around

     for the absence of support for infix operators in SGML.



     You can get oversize delimiters with the SIZE attribute,

     for example <BOX SIZE=large>(<LEFT>...<RIGHT>)</BOX>



     Note that the names of common functions are recognized

     by the parser without the need to use "&" and ";" around

     them, e.g. int, sum, sin, cos, tan, ...

-->



<!ELEMENT BOX - - ((%formula)*, (LEFT, (%formula)*)?,

                   ((OVER|ATOP|CHOOSE), (%formula)*)?,

                   (RIGHT, (%formula)*)?)>

<!ATTLIST BOX

        size  (normal|medium|large|huge) normal -- oversize delims -->



<!ELEMENT (OVER|ATOP|CHOOSE|LEFT|RIGHT) - O EMPTY>



<!-- Horizontal line drawn ABOVE contents

     The symbol attribute allows authors to supply

     an entity name for an accent, arrow symbol etc.

     Generalisation of LaTeX's overline command.

     

     e.g. <above sym=ssmile>x</above>

     places an upwardly turning curve above the "x"

 -->



<!ELEMENT ABOVE - - (%formula)+>

<!ATTLIST ABOVE sym ENTITY #IMPLIED>



<!-- Horizontal line drawn BELOW contents

     The symbol attribute allows authors to 

     supply an entity name for an arrow symbol etc.

     Generalisation of LaTeX's underline command.

 -->



<!ELEMENT BELOW - - (%formula)+>

<!ATTLIST BELOW sym ENTITY #IMPLIED>



<!-- Convenience tags for common accents:

     vec, bar, dot, ddot, hat and tilde

-->



<!ELEMENT (%mathvec) - - (%formula)+>





Dave Raggett                                                          Page 180



HTML 3.0                                                       28th March 1995



<!--

  T and BT are used to designate terms which should

  be rendered in an upright font (& bold face for BT)

-->



<!ELEMENT (T|BT) - - (%formula)+>

<!ATTLIST (T|BT) class NAMES #IMPLIED>



<!-- Roots  e.g. <ROOT>3<OF>1+x</ROOT> -->



<!ELEMENT ROOT - - ((%formula)+, OF, (%formula)+)>

<!ELEMENT OF - O (%formula)* -- what the root applies to -->



<!ELEMENT SQRT - - (%formula)* -- square root convenience tag -->



<!-- LaTeX like arrays. The COLDEF attribute specifies

     a single capital letter for each column determining

     how the column should be aligned, e.g. coldef="CCC"



        "L"     left

        "C"     center

        "R"     right

        

     An optional separator letter can occur between columns

     and should be one of + - or =, e.g. "C+C+C+C=C".

     Whitespace within coldef is ignored. By default, the

     columns are all centered.

     

     The ALIGN attribute alters the vertical position of the

     array as compared with preceding and following expressions.



     Use LDELIM and RDELIM attributes for delimiter entities.

     When the LABELS attribute is present, the array is

     displayed with the first row and the first column as

     labels displaced from the other elements. In this case,

     the first element of the first row should normally be

     left blank.



     Use &vdots; &cdots; and &ddots; for vertical, horizontal

     and diagonal ellipsis dots. Use &dotfill; to fill an array

     cell with horizontal dots (e.g. for a full row).

     Note &ldots; places the dots on the baseline, while &cdots;

     places them higher up.

-->



<!ELEMENT ARRAY - - (ROW)+>

<!ATTLIST ARRAY

        align (top|middle|bottom) middle -- vertical alignment --

        coldef  CDATA   #IMPLIED  -- column alignment and separator --

        ldelim  CDATA   #IMPLIED  -- stretchy left delimiter --

        rdelim  CDATA   #IMPLIED  -- stretchy right delimiter --

        labels (labels) #IMPLIED  -- TeX's \bordermatrix style -->





Dave Raggett                                                          Page 181



HTML 3.0                                                       28th March 1995



<!ELEMENT ROW - O (ITEM)*>

<!ELEMENT ITEM - O (%formula)*>

<!ATTLIST ITEM

        align   CDATA  #IMPLIED  -- override coldef alignment --

        colspan NUMBER 1         -- merge columns as per TABLE --

        rowspan NUMBER 1         -- merge rows as per TABLE -->



<!--================ Document Head ========================================-->



<![ %HTML.Deprecated [

    <!ENTITY % head.content "TITLE & ISINDEX? & BASE? & STYLE?

                              & META* & LINK* & RANGE* & NEXTID?">

]]>



<!ENTITY % head.nextid "">



<!ENTITY % head.content "TITLE & ISINDEX? & BASE? & STYLE?

                              & META* & LINK* & RANGE*">



<!ELEMENT HEAD O O  (%head.content)>



<!ELEMENT LINK - O EMPTY>

<!ATTLIST LINK

        href %URI #REQUIRED

        %linkExtraAttributes; >

        

<!ELEMENT RANGE - O EMPTY>

<!ATTLIST RANGE

        id    ID    #IMPLIED  -- for naming marked range --

        class NAMES #IMPLIED  -- for subclassing --

        from  IDREF #REQUIRED -- start of marked range --

        until IDREF #REQUIRED -- end of marked range --

        >



<!ELEMENT ISINDEX - O EMPTY>

<!ATTLIST ISINDEX

        href   %URI  #IMPLIED -- server handling queries --

        prompt CDATA #IMPLIED -- prompt message -->



<!--

    The BASE element gives the base URL for

    dereferencing relative URLs, e.g.



         <BASE href="http://foo.com/images">

         ...

         <IMG SRC="bar.gif">



    The image is deferenced to



         http://foo.com/images/bar.gif

-->



<!ELEMENT BASE - O EMPTY>



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HTML 3.0                                                       28th March 1995



<!ATTLIST BASE

        id   ID    #IMPLIED

        href %URI; #REQUIRED

        >



<![ %HTML.Deprecated [

    <!ELEMENT NEXTID - O EMPTY>

    <!ATTLIST NEXTID N CDATA #REQUIRED>

]]>



<!ELEMENT META - O EMPTY    -- Generic Metainformation -->

<!ATTLIST META

        http-equiv  NAME    #IMPLIED  -- HTTP response header name  --

        name        NAME    #IMPLIED  -- metainformation name       --

        content     CDATA   #REQUIRED -- associated information     --

        >



<!--

    A style sheet can be associated with the document using the

    LINK element, e.g. <LINK rel=style href="housestyle.dsssl">.

    Style overrides can be placed in the document head using the

    STYLE element, e.g.



        <style notation=dsssl-lite>

           dsss-lite stuff

        </style>



    Later on in the document you can use:



        <h2 class=bigcaps>Header with bigger than normal capitals</h2>

        <p class=abstract>A paragraph with a unique style of its own

        ...

    

    Statements in the given style notation 

        

    The tag names, class and id attributes are used in the style sheet

    notation to describe how to render matching elements.

-->



<!ENTITY % style-notations "dsssl-lite | w3c-style">

<!NOTATION dsssl-lite PUBLIC

      "ISO/IEC 10179:1995//NOTATION DSSSL Style Language//EN">

      

<!NOTATION w3c-style PUBLIC "IETF/RFC nnn/W3C Style Language//EN">



<!ELEMENT STYLE - O (#PCDATA)>

<!ATTLIST STYLE

    notation NOTATION (%style-notations;) #REQUIRED

>



<!--================ Document Structure ===================================-->



<!ENTITY % html.content "HEAD, BODY">



Dave Raggett                                                          Page 183



HTML 3.0                                                       28th March 1995





<!ELEMENT HTML O O  (%html.content)>

<!ENTITY % version.attr 'VERSION CDATA #FIXED "&HTML.Version;"'>



<!-- suggested roles are: TOC, DOC, DOCPART, HITLIST, DIALOG -->



<!ATTLIST HTML

        %version.attr;       -- report DTD version to application --

        urn   CDATA #IMPLIED -- universal resource name for this document --

        class NAMES #IMPLIED -- role of this document, eg table of contents --

        >



<!-- The END -->



















































































Dave Raggett                                                          Page 184



HTML 3.0                                                       28th March 1995



Glossary of Terms



Pasted from HTML 2.0 spec, this is now under revision ...



------------------------------------------------------------------------------

   The HTML specification uses these words with precise meanings:



   



   attribute 

       A characteristic quality of an element, other than type or

       content. 



       



   browser 

       A tool used to read electronic books. 



       



   document 

       For the purposes of this standard, an HTML instance. 



       



   element 

       A component of the hierarchical structure defined by the

       document type definition; it is identified in a document

       instance by descriptive markup, usually a start-tag and an

       end-tag. 



       



   HTML 

       HyperText Markup Language. 



       



   HTTP 

       A generic stateless object-oriented protocol, which may be used

       for many similar tasks by extending the commands, or "methods",

       used. For example, you might use HTTP for name servers and

       distributed object-oriented systems, With HTTP, the negotiation

       of data representation allows systems to be built independent of

       the development of new representations. For more information

       see:  http://www.w3.org/hypertext/WWW/Protocols/Overview.html



       



   markup 

       Text added to the data of a document to convey information about

       it. There are four different kinds of markup: descriptive markup

       (tags), references, markup declarations, and processing



Dave Raggett                                                          Page 185



HTML 3.0                                                       28th March 1995



       instructions. 



       



   MIME 

       Multipurpose Internet Mail Extensions as defined in Mechanisms

       for Specifying and Describing the Format of Internet Message

       Bodies, 09/23/1993. (Pages=81) (Format=.txt, .ps) (Obsoletes

       RFC1341) (Updated by RFC1590). 



       



   representation 

       The encoding of information for interchange. For example, HTML

       is a representation of hypertext. 



       



   rendering 

       Formatting and presenting information to human readers. 



       



   SGML 

       Standard Generalized Markup Language as defined in ISO

       8879:1986, Information Processing Text and Office Systems. 



       



   SGMLS 

       An SGML parser by James Clark, jjc@jclark.com, derived from the

       ARCSGML parser materials which were written by Charles F.

       Goldfarb. The source is available at

       ftp.ifi.uio.no/pub/SGML/SGMLS. 



       



   tag 

       Descriptive markup. There are two kinds of tags; start-tags and

       end-tags. 



       



   URI 

       Universal Resource Identifiers. Available by anonymous FTP as

       Postscript (www.w3.org/pub/www/doc/url.ps) or text

       (www.w3.org/pub/www/doc/url.txt) 



       



   W3 

       The World-Wide Web, a global information initiative. For

       bootstrap information, telnet www.w3.org or find documents at



Dave Raggett                                                          Page 186



HTML 3.0                                                       28th March 1995



       ftp://www.w3.org/pub/www/doc 



       







































































































Dave Raggett                                                          Page 187



HTML 3.0                                                       28th March 1995



References



Under revision ..



------------------------------------------------------------------------------

   The HTML specification cites these works:



   



   HTTP 

       HTTP: A Protocol for Networked Information. This document is

       available at  http://www.w3.org/WWW/Protocols/HTTP/HTTP2.html. 



       



   MIME 

       N. Borenstein, N. Freed, MIME (Multipurpose Internet Mail

       Extensions) Part One: Mechanisms for Specifying and Describing

       the Format of Internet Message Bodies, 09/23/1993. (Pages=81)

       (Format=.txt, .ps) (Obsoletes RFC1341) (Updated by RFC1590). 



       



   SGML 

       ISO 8879:1986, Information Processing Text and Office Systems

       Standard Generalized Markup Language (SGML). 



       



   SGMLS 

       An SGML parser by James Clark, jjc@jclark.com, derived from the

       ARCSGML parser materials which were written by Charles F.

       Goldfarb. The source is available at

       ftp.ifi.uio.no/pub/SGML/SGMLS. 



       



   URI 

       Universal Resource Identifiers. RFCxxx. Available by anonymous

       FTP as Postscript (info.cern.ch/pub/www/doc/url.ps) or text

       (info.cern.ch/pub/www/doc/url.txt) 



       



   W3 

       The World-Wide Web , a global information initiative. For

       bootstrap information, telnet info.cern.ch or find documents by

       ftp://info.cern.ch/pub/www/doc. 



       









Dave Raggett                                                          Page 188



HTML 3.0                                                       28th March 1995



Acknowledgments



Pasted from HTML 2.0 spec, this section is under revision ...



------------------------------------------------------------------------------

   The HTML document type was designed by Tim Berners-Lee at CERN as

   part of the 1990 World-Wide Web project. In 1992, Dan Connolly wrote

   the HTML Document Type Definition (DTD) and a brief HTML

   specification. 



   Since 1993, a wide variety of Internet participants have contributed

   to the evolution of HTML. NCSA Mosaic played a particularly

   important role in establishing HTML. Mosaic pioneered the addition

   of in-line images, image maps, nested lists and fill-out forms

   (derived from work on HTML+). Minor variations in the way extensions

   were supported by different browsers eventually led to the setting

   up of the HTML working group. The HTML 2.0 specification sets out a

   definitive standard for HTML, formalizing the de facto situation

   during 1994. 



   HTML+ was the result of my work on possible directions for extending

   HTML to meet the needs of information providers, e.g. to support

   forms, tables, text flow around figures and math. This work has now

   culminated in the current HTML 3.0 specification, which adds a range

   of important new features to HTML while preserving simplicity and

   backwards compatibility with existing documents. 



   I would like to express my special thanks to members of the Internet

   community on the www-talk, www-html and html-wg mailing lists; to

   people who have written to me in person, and to members of the

   SGML-Open who have been very supportive of the Web initiative.

   Thanks also to Hewlett Packard for funding my work on HTML. 



   Particular thanks are due to: 



   *   Terry Allen; O'Reilly & Associates; terry@ora.com 



   *   Marc Andreessen; Netscape Communications Corp;

       marca@netscape.com 



   *   Eric Bina; Netscape Communications Corp; ebina@netscape.com 



   *   Paul Burchard; The Geometry Center, University of Minnesota;

       burchard@geom.umn.edu 



   *   James Clark; jjc@jclark.com 



   *   Daniel W. Connolly; HaL Computer Systems; connolly@hal.com 



   *   Stephen DeRose; EBT; ??? steve@ebt.com 



   *   Roy Fielding; University of California, Irvine;

       fielding@ics.uci.edu 



Dave Raggett                                                          Page 189



HTML 3.0                                                       28th March 1995





   *   Jay Glicksman; Enterprise Integration Technology; jay@eit.com 



   *   Eduardo Gutentag; Sun Microsystems; eduardo@Eng.Sun.com 



   *   Bill Hefley; Software Engineering Institute, Carnegie Mellon

       University; weh@sei.cmu.edu 



   *   Chung-Jen Ho; Xerox Corporation; cho@xsoft.xerox.com 



   *   Mike Knezovich; Spyglass, Inc.; mike@spyglass.com 



   *   Tim Berners-Lee; CERN; timbl@info.cern.ch 



   *   Tom Magliery; NCSA; mag@ncsa.uiuc.edu 



   *   Murray Maloney; SCO Canada; murray@sco.com 



   *   Larry Masinter; Xerox Palo Alto Research Center;

       masinter@parc.xerox.com 



   *   Karen Olson Muldrow; HaL Computer Systems; karen@hal.com 



   *   Bill Perry, Spry, Inc., wmperry@spry.com 



   *   E. Corprew Reed; Cold Spring Harbor Laboratory; corp@cshl.org 



   *   Yuri Rubinsky; SoftQuad, Inc.; yuri@sq.com 



   *   Eric Schieler; Spyglass, Inc.; eschieler@spyglass.com 



   *   Eric Severson; Avalanche, Inc.; ??? severson@avalanche.com 



   *   Eric W. Sink; Spyglass, Inc.; eric@spyglass.com 



   *   Stuart Weibel; OCLC Office of Research; weibel@oclc.org 



   *   Chris Wilson; Spry, Inc.; cwilson@spry.com 



   Dave Raggett <dsr@w3.org>, February 1995.  





























Dave Raggett                                                          Page 190



