HTML.txt

HTML Working Group                                        T. Berners-Lee
INTERNET-DRAFT                                               D. Connolly
<draft-ietf-html-spec-03.txt>                                    MIT/W3C
Expires November 1, 1995                                   April 1, 1995


                   HyperText Markup Language -- 2.0


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 documents as Internet-Drafts.

   Internet-Drafts are draft documents valid for a maximum of six 
   months and may 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 other than as "work in 
   progress."

   To learn the current status of any Internet-Draft, please check the 
   "1id-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).

   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@oclc.org>. Discussions of the 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 represent 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 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. This specification roughly corresponds to 
   the capabilities of HTML in common use prior to June 1994. It is 
   defined as an application of ISO Standard 8879:1986 Information 
   Processing Text and Office Systems; Standard Generalized Markup 
   Language (SGML).

   The "text/html; version=2.0" Internet Media Type (RFC 1590) and 
   MIME Content Type (RFC 1521) is defined by this specification.

Contents

(@@ I'll regenerate this eventually)


1.  Introduction

1.1  Purpose

   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 has been in use by the World-Wide 
   Web (WWW) global information initiative since 1990. This 
   specification corresponds to the capabilities of HTML in common use 
   prior to June 1994 and referred to as "HTML 2.0".

   This specification defines HTML as an application of ISO Standard 
   8879:1986 Information Processing Text and Office Systems; Standard 
   Generalized Markup Language (SGML). SGML provides a formal 
   definition of the HTML syntax in the form of a Document Type 
   Definition (DTD).

   This specification also defines HTML as an Internet Media Type [7] 
   and MIME Content Type [4] called "text/html", or
   "text/html; version=2.0". As such, it defines the semantics of the
   HTML syntax and how that syntax should be interpreted by user agents.

1.2  Levels of Conformance

   Version 2.0 of HTML introduces a distinction between levels of 
   conformance:

   Level 0
       Indicates the minimum conformance level. When writing Level 0 
       documents, authors can be confident that the rendering at 
       different sites will reflect their intent.

   Level 1
       Includes Level 0 features plus features such as highlighting and 
       images.

   Level 2
       Includes all Level 0 and Level 1 features, plus forms.

1.3  Terminology

   The HTML specification uses these words with precise meanings:

   attribute
       A name/value pair: part of an element which is often used 
       to specify a characteristic quality of the element, other than 
       type or content.

   character
       An atom of information, for example a letter or a number.
       Graphic characters have associated glyphs, where as control
       characters have associated processing semantics.

   character encoding
       A mapping from sequences of octets to sequences of characters
       from a character repertoire; that is, a sequence of octets and a
       character encoding determines a sequence of characters.

   character number
       A number that determines a character, as per some character set.

   character repertoire
       A finite set of characters. The range of the mapping defined
       by a character set.

   character set
       A mapping of a subset of the integers onto a character
       repertoire. That is, for some set of integers (usually of
       the form {0, 1, 2, ..., N} ), a character set and an integer
       in that set determine a character. Conversely, a character
       and a character set determine the character's number (or,
       in rare cases, a few character numbers).

   conforming HTML user agent
       A user agent that conforms to this specification in its
       treatment of the Internet Media Type "text/html; version=2.0"

   document type definition (DTD)
       A DTD is a collection of declarations (entity, element, 
       attribute, link, map, etc.) in SGML syntax that defines the 
       components and structures available for a class (type) of 
       documents.

   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.

   entity
       data with an associated notation or interpretation; for
       example, a sequence of octets associated with an Internet Media
       Type.

   message entity
       a head and body. The head is a collection of name/value fields,
       and the body is a sequence of octets. The head defines the
       content type and content transfer encoding of the body.

   SGML document
       A set of entities, including the document entity, which is
       a text entity that conforms to the grammar specified in the SGML
       standard.

   HTML document
       An SGML document conforming to the HTML document type definition.

   HTTP
       The Hypertext Transfer Protocol [3] is the primary application-
       level protocol for the transfer of documents via the World-Wide 
       Web.

   (document) instance
       The document itself including the actual content with the actual 
       markup. Can be a single document or part of a document instance 
       set that follows the DTD.

   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 
       instructions.

   MIME
       The Multipurpose Internet Mail Extensions [4] provide the 
       ability to transfer non-textual data, such as graphics, audio 
       and fax, via Internet mail.

   minimally conforming HTML user agent
       A user agent that conforms to this specification in its
       treatment of the Internet Media Type "text/html; level=0;
       version=2.0"

   SGML
       Standard Generalized Markup Language [12] (see also [9] and [6]) 
       is a system for describing document types and markup languages
       to represent them.

   tag
       Markup that delimits an element. A tag includes a name which
       refers to an element declaration in the DTD, and may include
       attributes.

   text entity
       A finite sequence of characters. A text entity typically takes
       the form of a sequence of octets with some associated character
       encoding, transmitted over the network or stored in a file.

   user agent
       A component of a distributed system that presents an interface
       and processes requests on behalf of a user; for example, a www
       browser or a mail user agent.

   URI
       A Universal Resource Identifier [1] is a formatted string that
       serves as an identifier for a resource, typically on the
       Internet. URIs are used in HTML to identify the destination of
       hypertext links, the source of in-line images, and the object of
       form actions. URIs in common use include Uniform Resource
       Locators (URLs) [2] and Relative URLs [5].

   WWW
       The World-Wide Web is a hypertext-based, distributed information 
       system created by researchers at CERN in Switzerland. Users may 
       create, edit or browse hypertext documents. 
       <URL:http://www.w3.org/>

1.4  Imperatives

   may
       The implementation is not obliged to follow this in any way.

   must
       If this is not followed, the implementation does not conform to 
       this specification.

   shall
       If this is not followed, the implementation does not conform to 
       this specification.

   should
       If this is not followed, though the implementation officially 
       conforms to the specification, undesirable results may occur in 
       practice.

   typical
       Typical rendering is described for many elements. This is not a 
       mandatory part of the specification but is given as guidance for 
       designers and to help explain the uses for which the elements 
       were intended.

2.  HTML as an Application of SGML

   HTML is an application of ISO Standard 8879:1986 -- Standard 
   Generalized Markup Language (SGML) [12]. SGML is a system for 
   defining structured document types and markup languages to 
   represent instances of those document types. The SGML declaration 
   for HTML and the HTML document type definitions (DTDs) are provided 
   in Section 12.

   The term "HTML" refers to both the document type defined here and
   the markup language for representing instances of this document
   type.

2.1  SGML Documents

   An HTML document is an SGML document; that is, a set of entities,
   including the document entity, which is a text entity that conforms
   to the grammar specified in the SGML standard. The first production
   of that grammar separates an SGML document into three parts: an
   SGML declaration, a prologue, and an instance.

   For the purposes of this specification, the prologue is a DTD. This
   DTD describes another grammar: the start symbol is given in the
   doctype declaration; the terminals are data characters and tags,
   and the productions are determined by the element declarations. The
   instance must conform to the DTD, that is, it must be in the
   language defined by this grammar.

   The SGML declaration determines the lexicon of the grammar. It
   specifies the document character set, which determines a character
   repertoire that contains all characters used in all text entities
   in the document, and the character numbers associated with those
   characters.

   The SGML declaration also specifies the syntax character set of the
   document, and a few other parameters that bind the abstract syntax
   of SGML to a concrete syntax. This concrete syntax determines how
   each text entity is mapped to a sequence of terminals in the grammar
   of the prologue.

   For example, consider the following document:

    <!DOCTYPE html PUBLIC "-//IETF//DTD HTML 2.0//EN">
    <title>Parsing Example</title>
    <p>Some text. <em>&#42;wow&#42;</em>

   By application convention, the SGML declaration is the one given in
   section 13.2. Hence the document character set is ISO-8859-1(@@)
   and the markup "&#42;" represents an asterisk character.

   The instance is regarded as the following sequence of terminals:

    TITLE start tag
    data characters: "Parsing Example"
    TITLE end tag
    P start tag
    data characters "Some text. "
    EM start tag
    "*wow*"
    EM end tag

   The start symbol of the DTD grammar is HTML, and the productions
   are given in the public text identified by "-//IETF//DTD HTML
   2.0//EN" (Section 13.3). Hence the terminals above parse as:

   HTML
    |
    \-HEAD,     BODY
       |	 |
       \-TITLE	 \-P
           |	   |
	   |	   \-<P>,"Some text. ",EM
           |                            |
           |                            \-<EM>,"*wow*",</EM>
           \-<TITLE>,"Parsing Example",</TITLE>

2.2  HTML Lexical Syntax

   The syntax character set for all HTML documents is ISO-646 (@@ full
   name). A minimally conforming HTML user agent must support the SGML
   declaration in section 13@@, which specifies ISO Latin 1 (@@full
   name) as the document character set; it may support other SGML
   declarations, in particular, SGML declarations with other document
   character sets.

   A complete discussion of the mapping of a sequence of characters to
   a sequence of tags and data is left to the SGML standard. This
   section is only a summary.

2.2.1 Data Characters

   Any sequence of characters that do not constitute markup (see
   "Delimiter Recognition," section @@@ of the SGML standard) are
   mapped directly to strings of data characters. Some markup also
   maps to data character strings. Numeric character references also
   map to single-character strings, via the document character
   set. Each reference to one of the general entities defined in the
   HTML DTD also maps to a single-character string.

   For example,

       abc&lt;def    => "abc","<","def"
       abc&#60;def   => "abc","<","def"

   Note that the terminating semicolon is only necessary when the
   character following the reference would otherwise be recognized as
   markup:

       abc &lt def     => "abc ","<"," def"
       abc &#60 def    => "abc ","<"," def"

   And note that an ampersand is only recognized as markup when it
   is followed by a letter or number:

       abc & lt def    => "abc & lt def"
       abc & 60 def    => "abc & 60 def"

   A useful technique for translating plain text to HTML is to replace
   each '<', '&', and '>' by an entity reference or numeric character
   reference as follows:

                 ENTITY      NUMERIC
       CHARACTER REFERENCE   CHAR REF     CHARACTER DESCRIPTION
         &       &amp;       &#38;        Ampersand 
         <       &lt;        &#60;        Less than
         >       &gt;        &#62;        Greater than


       Note: There are SGML features, CDATA and RCDATA, to allow 
       most "<", ">", and "&" characters to be entered without the 
       use of entity references. Because these features tend to be 
       used and implemented inconsistently, and because they 
       require 8bit characters to represent non-ASCII characters, 
       they are not used in this version of the HTML DTD.

2.2.1 Tags

   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 ">"; end tags are delimited by "</" 
   and ">". An example is:

       <H1>This is a Heading</H1>

   Some elements only have a start tag without an end tag. For 
   example, to create a line break, you use the <BR> tag. 
   Additionally, the end tags of some other elements, such as 
   Paragraph (<P>), List Item (<LI>), Definition Term (<DT>), and 
   Definition Description (<DD>) elements, may be omitted.

   The content of an element is a sequence of characters and nested 
   elements. Some elements, such as anchors, cannot be nested. Anchors 
   and character highlighting may be put inside other constructs. See
   the HTML DTD for full details.

       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.

2.2.2 Names

   A name consists of a letter followed by up to 71 letters, digits, 
   periods, or hyphens. Element names are not case sensitive, but 
   entity names are. For example, <BLOCKQUOTE>, <BlockQuote>, and 
   <blockquote> are equivalent, whereas &amp; is different from &AMP;.

   In a start tag, the element name must immediately follow the tag 
   open delimiter "<".

2.2.3 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:

      o A string literal, delimited by single quotes or double quotes 
        and not containing any occurrences of the delimiting character.

      o 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">

       Note: Some historical 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, it should be represented with a numeric
       character reference, such as in: <IMG SRC="eq1.jpg" alt="a
       &#62; b">

   A useful technique for computing an attribute value literal for a
   given string is to replace each quote and space character by an
   entity reference or numeric character reference as follows:

                 ENTITY      NUMERIC
       CHARACTER REFERENCE   CHAR REF     CHARACTER DESCRIPTION
         TAB                 &#9;         Tab
         LF                  &#10;        Line Feed
         CR                  &#13;        Carriage Return
                             &#32;        Space
         "       &quot;      &#34;        Quotation mark 
         &       &amp;       &#38;        Ampersand 

   For example:

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

       Note: Some historical 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.

   Note that the SGML declaration in section 13.3 limits the length of
   an attribute value to 1024 characters.

   Attributes with a declared value of NAME, such as ISMAP and 
   COMPACT, may be written using a minimized syntax. The markup:

       <UL COMPACT="compact">

   can be written using a minimized syntax:

       <UL COMPACT>

       Note: Some historical implementations only understand the 
       minimized syntax.

2.2.5 Comments

   To include comments in an HTML document that will be eliminated in
   the mapping to terminals, 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>
       <!-- $Id$ -->
       </HEAD>

       Note: Some historical HTML implementations incorrectly consider 
       any ">" character to be the termination of a comment.

2.3  Example HTML Document

       <!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML//EN">
       <HTML>
       <!-- Here's a good place to put a comment. -->
       <HEAD>
       <TITLE>Structural Example</TITLE>
       </HEAD><BODY>
       <H1>First Header</H1>
       <P>This is a paragraph in the example HTML file. Keep in mind 
       that the title does not appear in the document text, but that 
       the header (defined by H1) does.</P>
       <OL>
       <LI>First item in an ordered list.
       <LI>Second item in an ordered list.
         <UL COMPACT>
         <LI> Note that lists can be nested;
         <LI> Whitespace may be used to assist in reading the 
              HTML source.
         </UL>
       <LI>Third item in an ordered list.
       </OL>
       
       <P>This is an additional paragraph. Technically, end tags are 
       not required for paragraphs, although they are allowed. You can 
       include character highlighting in a paragraph. <EM>This sentence 
       of the paragraph is emphasized.</EM> Note that the &lt;/P&gt; 
       end tag has been omitted.
       <P>
       <IMG SRC ="triangle.xbm" alt="Warning:">
       Be sure to read these <b>bold instructions</b>.
       </BODY></HTML>

3.  HTML as an Internet Media Type

   An HTML user agent allows users to interact with resources which
   have HTML representations. At a minimum, it must allow users to
   examine and navigate the content of HTML Level 0 documents. Level 1
   HTML user agents must be able preserve all formatting distinctions
   represented in an HTML Level 1 document, and be able to
   simultaneously present resources referred to by IMG elements. (they
   may ignore some formatting distinctions or IMG resources at the
   request of the user). Fully conforming HTML user agents, that is
   Level 2 HTML user agents, must support form entry and submission.

3.1  text/html media type

   This specification defines the Internet  Media Type [7] (formerly 
   referred to as the MIME Content Type [4]) called  "text/html". The 
   following is to be registered with IANA [8].

       Media Type name:          text

       Media subtype name:       html

       Required parameters:      none

       Optional parameters:      level, version, charset

       Encoding considerations:  any encoding is allowed

       Security considerations:  [Section 14]

   The optional parameters are defined as follows:

   Level
       The level parameter specifies the feature set used in the 
       document. The level is an integer number, implying that any 
       features of same or lower level may be present in the document. 
       Levels 0, 1 and 2 are defined by this specification. Level 2 is 
       the default.

   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 of the HTML DTD. This specification defines
       version 2.0.

   Charset
       The charset parameter (as defined in section 7.1.1 of RFC 1521
       [4]) may be given to specify the encoding used to represent the
       HTML document as a sequence of octets. The default value is
       outside the scope of this specification; but for example, the
       default is US-ASCII in the context of MIME mail, and ISO-8859-1
       in the context of HTTP.

3.2  HTML Document Representation

   A message entity with a content type of "text/html" represents an HTML
   document, consisting of a single text entity. The charset parameter
   (whether implicit or explicit) identifies a character encoding. The
   text entity consists of the characters determined by this character
   encoding and the octets of the body of the message entity.

   The SGML declaration of the document is a function of the charset
   parameter. If the charset parameter is US-ASCII or ISO-8859-1, the
   SGML declaration in section 13@@ applies. Other charset parameter
   values are reserved for future use.

   NOTE: A generalized convention for mapping charset parameter values
   to SGML declarations is expected to be specified in a future
   version of this specification.

3.2.1  Conventional Handling of Undeclared Markup Errors

   To facilitate experimentation and interoperability between
   implementations of various versions of HTML, the installed base of
   HTML user agents supports a superset of the HTML 2.0 language by
   reducing it to HTML 2.0: markup in the form of a start tag or end
   tag whose generic identifier is not declared is mapped to nothing
   during tokenization. Undeclared attributes are treated similarly.
   The entire attribute specification of an unknown attribute (i.e.,
   the unknown attribute and its value, if any) should be ignored.  On
   the other hand, references to undeclared entities should be treated
   as data characters.

   For example:

     <div class=chapter><h1>foo</h1><p>...</div>
	  => <H1>,"foo",</H1>,<P>,"..."

     xxx <P ID=z23> yyy
          => "xxx ",<P>," yyy

     Let &alpha; and &beta; be finite sets.
	  => "Let &alpha; and &beta; be finite sets."

   Support for notifying the user of such errors is encouraged.

   Information providers should keep in mind that this convention is
   not binding: unspecified behavior may result, as such markup is
   not conforming to this specification.


3.2.1  Conventional Representation of Newlines

   SGML specifies that a text entity is a sequence of records, each
   beginning with a record start character and ending with a record
   end character (characters numbered 10 and 13 respectively).

   MIME specifies that a body of type text/* is a sequence of lines,
   each terminated by CRLF, that is octets 10, 13.

   In practice, HTML documents are frequently represented and
   transmitted using an end of line convention that depends on the
   conventions of the source of the document; frequently, that
   representation consists of CR only, LF only, or CR LF
   combination. Hence the decoding of the octets will often result in
   a text entity with some missing record start and record end
   characters.

   Since there is no ambiguity, HTML user agents are encouraged to
   infer the missing record start and end characters.

   An HTML user agent should treat end of line in any of its
   variations as a word space in all contexts except
   preformatted text. Within preformatted text, an HTML user agent
   should expect to treat any of the three common representations of
   end-of-line as starting a new line.

4.  Document Structure

   To identify information as an HTML document conforming to this 
   specification, each document should start with the prologue:

       <!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN">

       Note: If the body of a text/html body part does not begin 
       with a document type declaration, an HTML user agent should 
       infer the above document type declaration.

   HTML user agents are required to support the above document type
   declaration, the following document type declarations, and no
   others.

       <!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0 Level 0//EN">
       <!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0 Level 1//EN">
       <!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0 Level 2//EN">

   In particular, they may support other formal public identifiers, or
   document types altogether. They may support an internal declaration
   subset with supplemental entity, element, and other markup
   declarations, or they may not.

   HTML documents may contain an <HTML> tag at the beginning
   (immediately after the prologue) and an </HTML> tag at the end.

   The HTML document element is organized as a head and a body, much
   like a memo or a mail message. Within the head, you can specify the
   title and other information about the document. Within the body,
   you can structure text into paragraphs and lists, as well as
   highlight phrases and create links, using HTML elements.

       Note: Technically, the start and end tags for HTML, Head, 
       and Body elements are omissible; however, this is not 
       recommended since the head/body structure allows an 
       implementation to determine certain properties of a 
       document, such as the title, without parsing the entire 
       document.

4.1  HTML Document Element

   <HTML> ... </HTML>                                           Level 0

   The HTML element contains the Head and Body elements.

4.2  Head

   <HEAD> ... </HEAD>                                           Level 0

   The head of an HTML document is an unordered collection of 
   information about the document. It requires the Title element 
   between <HEAD> and </HEAD> tags:

       <HEAD>
       <TITLE>Introduction to HTML</TITLE>
       </HEAD>

4.3  Body

   <BODY> ... </BODY>                                           Level 0

   The Body element identifies the body component of an HTML document. 
   Specifically, the body of a document may contain links, text, and 
   formatting information within <BODY> and </BODY> tags.

5.  Document Metainformation Elements

5.1  Title

   <TITLE> ... </TITLE>                                         Level 0

   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 history lists and as a label for the window displaying 
   the document. Unlike headings, titles are not rendered in the text 
   of a document itself.

   The Title element must occur within the head of the document, and 
   must not contain anchors, paragraph tags, or highlighting. Only one 
   title is allowed in a document.

       Note: The length of a title is not limited; however, long 
       titles may be truncated in some applications. To minimize 
       this possibility, titles should be 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 "Introduction to HTML Elements."

5.2  Base

   <BASE>                                                       Level 0

   The Base element allows the URL [2] 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 [5].

   The Base element has one attribute, HREF, which identifies the 
   absolute base URL.

5.3  Isindex

   <ISINDEX>                                                    Level 0

   The Isindex element tells the user agent that the document is an 
   index. This means that the reader may request a keyword search on 
   the resource by adding a question mark to the end of the document 
   address, followed by a list of keywords separated by plus signs.

   The Isindex element is usually generated by the network server from 
   which the document was obtained via a URI. The server must have a 
   search engine that supports this feature for the resource. If the 
   document URI is unknown to the user agent, <isindex> must be 
   ignored.

5.4  Link

   <LINK>                                                       Level 0

   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.

   Typical uses are to indicate authorship, related indexes and 
   glossaries, older or more recent versions, etc. Links can indicate 
   a static tree structure in which the document was authored by 
   pointing to a "parent" and "next" and "previous" document, for 
   example.

   Servers may also allow links to be added by those who do not have 
   the right to alter the body of a document.

5.5  Meta

   <META>                                                       Level 0

   The META element is used within the HEAD element to embed document 
   metainformation not defined by other HTML elements. META elements 
   can be extracted by servers and/or clients for use in identifying, 
   indexing, and cataloging specialized document metainformation.

   Although it is generally preferable to use named elements which 
   have well-defined semantics for each type of metainformation (e.g. 
   TITLE), the META element is provided for situations where strict 
   SGML parsing is necessary and the local DTD is not extensible. HTML 
   user agents may use the META element's content if they recognize 
   and understand the semantics identified by the NAME or HTTP-EQUIV 
   attributes, and may treat the content as metainformation (and not 
   render it) even when they do not recognize the name.

   In addition, HTTP servers may wish to read the content of the 
   document HEAD to generate header fields corresponding to any 
   elements defining a value for the attribute HTTP-EQUIV. Note, 
   however, that the method by which the server extracts document 
   metainformation is not part of this specification, nor can it be 
   assumed by authors that any given server will be capable of 
   extracting it. The META element only provides an extensible 
   mechanism for identifying and embedding document metainformation -- 
   how it may be used is up to the individual server implementation 
   and the HTML user agent.

   Attributes of the META element:

   HTTP-EQUIV
       This attribute binds the element to an HTTP header field. It 
       means that if you know the semantics of the HTTP header field 
       named by this attribute, then you can process the contents based 
       on a well-defined syntactic mapping, whether or not your DTD 
       tells you anything about it. HTTP header field names are not 
       case sensitive. If not present, the attribute NAME should be 
       used to identify this metainformation and the content should not 
       be used within an HTTP response header.

   NAME
       Metainformation name. If the NAME attribute is not present, the 
       name can be assumed to be equal to the value of HTTP-EQUIV.

   CONTENT
       The metainformation content to be associated with the given 
       name. If multiple META elements are provided with the same name, 
       their combined contents--concatenated as a comma-separated list--
       is the value associated with that name.

   Examples

   If the document contains:

       <META HTTP-EQUIV="Expires"
             CONTENT="Tue, 04 Dec 1993 21:29:02 GMT">
       <meta http-equiv="Keywords" CONTENT="Fred, Barney">
       <META HTTP-EQUIV="Reply-to"
             content="fielding@ics.uci.edu (Roy Fielding)">

   then the server (if so configured) may include the following 
   headers:

       Expires: Tue, 04 Dec 1993 21:29:02 GMT
       Keywords: Fred, Barney
       Reply-to: fielding@ics.uci.edu (Roy Fielding)

   as part of the HTTP response to a GET or HEAD request for that 
   document.

   When the HTTP-EQUIV attribute is not present, the server should not 
   generate an HTTP response header for the metainformation; e.g.,

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

   would never generate an HTTP response header, but would still allow 
   HTML user agents to identify and make use of that metainformation.

   The Meta element should never be used to define information that 
   should be associated with an existing HTML element. An example of 
   an inappropriate use of the Meta element is:

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

   Do not name an HTTP-EQUIV equal to a response header that should 
   normally only be generated by the HTTP server. Example names that 
   are inappropriate include "Server", "Date", and "Last-modified" -- 
   the exact list of inappropriate names is dependent on the 
   particular server implementation. We recommend that servers ignore 
   any META elements which specify HTTP-equivalents which are equal 
   (case-insensitively) to their own reserved response headers.

5.6  Nextid

   <NEXTID>                                                     Level 0

   The Nextid element is a parameter read and generated by text 
   editing software to create unique identifiers. This tag takes a 
   single attribute which is the next document-wide alpha-numeric 
   identifier to be allocated of the form z123:

       <NEXTID N=Z27>

   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.

   HTML user agents may ignore the Nextid element. Support for the 
   Nextid element does not impact HTML user agents in any way.

6.  Data Characters

    An HTML user agent should present the body of an HTML document as
    a collection of typeset paragraphs and preformatted text. Except
    for the PRE element, each block structuring element is regarded as
    a paragraph by taking the data characters in its content and the
    content of its descendant elements, concatenating them, and
    splitting the result into words, separated by space, tab, or
    record end characters (and perhaps hyphen characters). The
    sequence of words is typeset as a paragraph by breaking it into
    lines.

6.1 The ISO Latin 1 Character Repertoire

   Conforming HTML user agents are required to support the US-ASCII
   [10] or ISO-8859-1 [11] character encodings, and the @@fullname ISO
   Latin 1 document character set.

   The character repertoire shared by these two is known as Latin
   Alphabet No. 1, or simply Latin-1.  Latin-1 includes characters
   from most Western European languages, as well as a number of
   control characters.  Latin-1 also includes a non-breaking space, a
   soft hyphen indicator, 93 graphical characters, 8 unassigned
   characters, and 25 control characters.

   NOTE: Use the non-breaking space and soft hyphen indicator characters is 
   discouraged because support for them is not widely deployed.

   In SGML applications, the use of control characters is limited in 
   order to maximize the chance of successful interchange over 
   heterogeneous networks and operating systems. In HTML, only three 
   control characters are allowed: Horizontal Tab (HT, encoded as 9 
   decimal in US-ASCII and ISO-8859-1), Carriage Return, and Line Feed.

   The HTML DTD references the Added Latin 1 entity set, to allow
   mnemonic representation of Latin 1 characters using only the widely
   supported ASCII character repertoire. For example:

       Kurt G&ouml;del was a famous logician and mathematician.

   See Section 13.2 for a table of the "Added Latin 1" entities, and
   section 13.3 for a table of the characters of ISO-8859-1.

7.  Data Elements

7.1  Line Break

   <BR>                                                         Level 0

   The Line Break element specifies a line break in a paragraph or
   preformatted text section. A new line should indent the same as
   that of line-wrapped text.

   Example of use:

       <P> Pease porridge hot<BR>
       Pease porridge cold<BR>
       Pease porridge in the pot<BR>
       Nine days old.

7.2  Horizontal Rule

   <HR>                                                         Level 0

   A Horizontal Rule element is a divider between sections of text 
   such as a full width horizontal rule or equivalent graphic.

   Example of use:

       <BODY>
       ...
       <HR>
       <ADDRESS>February 8, 1995, CERN</ADDRESS>
       </BODY>

7.3  Image

   <IMG>                                                        Level 0

   The Image element is used to incorporate in-line graphics 
   (typically icons or small graphics) into an HTML document. This 
   element cannot be used for embedding other HTML text.

   HTML user agents that cannot render in-line images ignore the 
   Image element unless it contains the ALT attribute. Note that some 
   HTML user agents can render linked graphics but not in-line 
   graphics. If a graphic is essential, you may want to create a link 
   to it rather than to put it in-line. If the graphic is not 
   essential, then the Image element is appropriate.

   The Image element, which is empty (no closing tag), has these 
   attributes:

   ALIGN
       The ALIGN attribute accepts the values TOP or MIDDLE or BOTTOM, 
       which specifies if the following line of text is aligned with 
       the top, middle, or bottom of the graphic.

   ALT
       Optional text as an alternative to the graphic for rendering in 
       non-graphical environments. Alternate text should be provided 
       whenever the graphic is not rendered. Alternate text is 
       mandatory for Level 0 documents. Example of use:

       <IMG SRC="triangle.xbm" ALT="Warning:"> Be sure to read these 
       instructions.

   ISMAP
       The ISMAP (is map) attribute identifies an image as an image 
       map. Image maps are graphics in which certain regions are mapped 
       to URLs. By clicking on different regions, different resources 
       can be accessed from the same graphic. Example of use:

       <A HREF="http://machine/htbin/imagemap/sample">
       <IMG SRC="sample.xbm" ISMAP>
       </A>

   SRC
       The value of the SRC attribute is the URL of the document to be 
       embedded; only images can be embedded, not HTML text. Its syntax 
       is the same as that of the HREF attribute of the <A> tag. SRC is 
       mandatory. Image elements are allowed within anchors.

   Example of use:

       <IMG SRC="triangle.xbm">Be sure to read these instructions.

8.  Character Format Elements

   Character format elements are used to specify either the logical 
   meaning or the physical appearance of marked text without causing a 
   paragraph break. Like most other elements, character format 
   elements include both opening and closing tags. Only the characters 
   between the tags are affected:

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

   Character format tags may be ignored by minimal HTML applications.

   Character format tags are interpreted from left to right as they 
   appear in the flow of text. Level 1 user agents must render 
   highlighted text distinctly from plain text. Additionally, EM 
   content must be rendered as distinct from STRONG content, and B 
   content must rendered as distinct from I content.

   Character format elements may be nested within the content of other 
   character format elements; however, HTML user agents are not 
   required to render nested character format elements distinctly from 
   non-nested elements:

       plain <B>bold <I>italic</I></B> may the rendered the same as 
       plain <B>bold </B><I>italic</I>

8.1  Semantic Format Elements

   Note that typical renderings for semantic format elements vary 
   between applications. If a specific rendering is necessary -- for 
   example, when referring to a specific text attribute as in "The 
   italic parts are mandatory" -- a physical formatting element can be 
   used to ensure that the intended rendered is used where possible.

   Note that different semantic elements may be rendered in the same 
   way.

8.1.1 Citation

   <CITE>...</CITE>                                             Level 1

   The Citation element specifies a citation, typically rendered as 
   italics.

8.1.2 Code

   <CODE> ... </CODE>                                           Level 1

   The Code element indicates an example of code, typically rendered 
   in a monospaced font. This should not be confused with the 
   Preformatted Text element.

8.1.3 Emphasis

   <EM> ... </EM>                                               Level 1

   The Emphasis element indicates typographic emphasis, typically 
   rendered as italics.

8.1.4 Keyboard

   <KBD> ... </KBD>                                             Level 1

   The Keyboard element indicates text typed by a user, typically 
   rendered in a monospaced font. This is commonly used in instruction 
   manuals.

8.1.5 Sample

   <SAMP> ... </SAMP>                                           Level 1

   The Sample element indicates a sequence of literal characters, 
   typically rendered in a monospaced font.

8.1.6 Strong

   <STRONG> ... </STRONG>                                       Level 1

   The Strong element indicates strong typographic emphasis, typically 
   rendered in bold.

8.1.7 Variable

   <VAR> ... </VAR>                                             Level 1

   The Variable element indicates a variable name, typically rendered 
   as italic.

8.2  Physical Format Elements

   Physical format elements are used to specify the format of marked 
   text.

8.2.1 Bold

   <B> ... </B>                                                 Level 1

   The Bold element specifies that the text should be rendered in 
   boldface, where available. Otherwise, an alternative mapping is 
   allowed.

8.2.2 Italic

   <I> ... </I>                                                 Level 1

   The Italic element specifies that the text should be rendered in an 
   italic font, where available. Otherwise, an alternative mapping is 
   allowed.

8.2.3 Teletype

   <TT> ... </TT>                                               Level 1

   The Teletype element specifies that the text should be rendered in 
   a fixed-width typewriter font.

9.  Hypertext Elements

9.1  Anchor

   <A> ... </A>                                                 Level 0

   An anchor is a marked section of text that is the start and/or 
   destination of a hypertext link. Anchor elements are defined by the 
   <A> tag. The <A> tag accepts several attributes; at least one of 
   the NAME and HREF attributes is required.

   Attributes of the <A> tag:

9.1.1 HREF

   If the HREF attribute is present, the text between the opening and 
   closing anchor tags becomes hypertext. If this hypertext is 
   selected by readers, they are moved to another document, or to a 
   different location in the current document, whose network address 
   is defined by the value of the HREF attribute.

   Example:

       See <A HREF="http://www.hal.com/">HaL</A>'s information for more 
       details.

   In this example, selecting "HaL" takes the reader to a document at 
   http://www.hal.com. The format of the network address is specified 
   in the URI specification for print readers.

   With the HREF attribute, the form HREF="#identifier" can refer to 
   another anchor in the same document.

   Example:

       The <A HREF="#glossary">glossary</A> defines terms used in this 
       document.

   In this example, selecting "glossary" takes the reader to another 
   anchor (i.e., <A NAME="glossary">Glossary</A>) in the same 
   document. The NAME attribute is described below. If the anchor is 
   in another document, the HREF attribute may be relative to the 
   document's address or the specified base address (see Section 5.2).

9.1.2 NAME

   If present, the NAME attribute allows the anchor to be the target 
   of a link. The value of the NAME attribute is an identifier for the 
   anchor. Identifiers are arbitrary strings but must be unique within 
   the HTML document.

   Example of use:

       <A NAME="coffee">Coffee</A> is an example of ...
       ... An example of this is <A HREF="#coffee">coffee</A>.

   Another document can then make a reference explicitly to this 
   anchor by putting the identifier after the address, separated by a 
   hash sign:

       <A HREF="drinks.html#coffee">

9.1.3 TITLE

   The TITLE attribute is informational only. If present, the TITLE 
   attribute should provide the title of the document whose address is 
   given by the HREF attribute.  The TITLE attribute is useful for at 
   least two reasons. The HTML user agent may display the title of 
   the document prior to retrieving it, for example, as a margin note 
   or on a small box while the mouse is over the anchor, or while the 
   document is being loaded. Another reason is that documents that are 
   not marked up text, such as graphics, plain text and Gopher menus, 
   do not have titles. The TITLE attribute can be used to provide a 
   title to such documents. When using the TITLE attribute, the title 
   should be valid and unique for the destination document.

9.1.4 REL

   The REL attribute gives the relationship(s) described by the 
   hypertext link from the anchor to the target. The value is a 
   whitespace-separated list of relationship names. Relationship names 
   and their semantics will be registered by the W3 Consortium. The 
   default relationship is void. The REL attribute is only used when 
   the HREF attribute is present.

9.1.5 REV

   The REV attribute is the same as the REL attribute, but the 
   semantics of the link type are in the reverse direction. A link 
   from A to B with REL="X" expresses the same relationship as a link 
   from B to A with REV="X". An anchor may have both REL and REV 
   attributes.

9.1.6 URN

   If present, the URN attribute specifies a uniform resource name 
   (URN) for a target document. The format of URNs is under discussion 
   (1995) by various working groups of the Internet Engineering Task 
   Force.

9.1.7 METHODS

   The METHODS attributes of anchors and links provide information 
   about the functions that the user may perform on an object. These 
   are more accurately given by the HTTP protocol when it is used, but 
   it may, for similar reasons as for the TITLE attribute, be useful 
   to include the information in advance in the link. For example, the 
   HTML user agent may chose a different rendering as a function of 
   the methods allowed; for example, something that is searchable may 
   get a different icon.

   The value of the METHODS attribute is a whitespace-separated list 
   of HTTP methods supported by the object for public use.

10.  Block Structuring Elements

   The following elements may be included in the body of an HTML 
   document:

10.1  Paragraph

   <P> ... </P>                                                 Level 0

   The Paragraph element indicates a paragraph. The exact indentation, 
   leading space, etc. of a paragraph is not defined and may be a 
   function of other tags, style sheets, etc.

   Typically, paragraphs are surrounded by a vertical space of one 
   line or half a line. This is typically not the case within the 
   Address element and is never the case within the Preformatted Text 
   element. With some HTML user agents, the first line in a paragraph 
   is indented.

   Example of use:

       <H1>This Heading Precedes the Paragraph</H1>
       <P>This is the text of the first paragraph.
       <P>This is the text of the second paragraph. Although you do not 
       need to start paragraphs on new lines, maintaining this 
       convention facilitates document maintenance.</P>
       <P>This is the text of a third paragraph.</P>

10.2  Preformatted Text

   <PRE> ... </PRE>                                             Level 0

   The Preformatted Text element presents blocks of text in fixed-
   width font, and so is suitable for text that has been formatted on 
   screen.

   The WIDTH attribute specifies the maximum number of characters for
   a line and allows an HTML user agent to select a suitable font and
   indentation. The WIDTH attribute defaults to 80. Widths of 40, 80
   and 132 characters should be presented optimally, with other widths
   being rounded up.

   Within preformatted text:

      o Line breaks within the text are rendered as a move to the 
        beginning of the next line.

      o The <P> tag should not be used. If found, it should be rendered 
        as a move to the beginning of the next line.

      o Anchor elements and character highlighting elements may be used.

      o Elements that define paragraph formatting (headings, address, 
        etc.) must not be used.

      o The horizontal tab character (encoded in US-ASCII and ISO-8859-1
        as decimal 9) must be interpreted as the smallest positive 
        nonzero number of spaces which will leave the number of 
        characters so far on the line as a multiple of 8. Its use is 
        not recommended however.

       Note: References to the "beginning of a new line" do not 
       imply that the renderer is forbidden from using a constant 
       left indent for rendering preformatted text. The left indent 
       may be constrained by the width required.

   Example of use:

       <PRE WIDTH="80">
       This is an example line.
       </PRE>

       Note: Within a Preformatted Text element, the constraint 
       that the rendering must be on a fixed horizontal character 
       pitch may limit or prevent the ability of the HTML 
       user agent to faithfully render character formatting 
       elements.

10.3  Address

   <ADDRESS> ... </ADDRESS>                                     Level 0

   The Address element specifies such information as address, 
   signature and authorship, often at the top or bottom of a document.

   Typically, an Address is rendered in an italic typeface and may be 
   indented. The Address element implies a paragraph break before and 
   after.

   Example of use:

       <ADDRESS>
       Newsletter editor<BR>
       J.R. Brown<BR>
       JimquickPost News, Jumquick, CT 01234<BR>
       Tel (123) 456 7890
       </ADDRESS>

10.4  Blockquote

   <BLOCKQUOTE> ... </BLOCKQUOTE>                               Level 0

   The Blockquote element is used to contain text quoted from another 
   source.

   A typical rendering might be a slight extra left and right indent, 
   and/or italic font. The Blockquote element causes a paragraph 
   break, and typically provides space above and below the quote.

   Single-font rendition may reflect the quotation style of Internet 
   mail by putting a vertical line of graphic characters, such as the 
   greater than symbol (>), in the left margin.

   Example of use:

       I think the poem ends
       <BLOCKQUOTE>
       <P>Soft you now, the fair Ophelia. Nymph, in thy orisons, be all 
       my sins remembered.
       </BLOCKQUOTE>
       but I am not sure.

10.5  Headings

   <H1> ... </H1> through <H6> ... </H6>                        Level 0

   HTML defines six levels of heading. A Heading element implies all 
   the font changes, paragraph breaks before and after, and white 
   space necessary to render the heading.

   The highest level of headings is H1, followed by H2 ... H6.

   Example of use:

       <H1>This is a heading</H1>
       Here is some text
       <H2>Second level heading</H2>
       Here is some more text.

   The rendering of headings is determined by the HTML user agent, 
   but typical renderings are:

   <H1> ... </H1>
       Bold, very-large font, centered. One or two blank lines above 
       and below.

   <H2> ... </H2>
       Bold, large font, flush-left. One or two blank lines above and 
       below.

   <H3> ... </H3>
       Italic, large font, slightly indented from the left margin. One 
       or two blank lines above and below.

   <H4> ... </H4>
       Bold, normal font, indented more than H3. One blank line above 
       and below.

   <H5> ... </H5>
       Italic, normal font, indented as H4. One blank line above.

   <H6> ... </H6>
       Bold, indented same as normal text, more than H5. One blank line 
       above.

   Although heading levels can be skipped (for example, from H1 to 
   H3), this practice is discouraged as skipping heading levels may 
   produce unpredictable results when generating other representations 
   from HTML.

10.6  List Elements

   HTML supports several types of lists, all of which may be nested.

10.6.1 Definition List

   <DL> ... </DL>                                               Level 0

   A definition list is a list of terms and corresponding definitions. 
   Definition lists are typically formatted with the term flush-left 
   and the definition, formatted paragraph style, indented after the 
   term.

   Example of use:

       <DL>
       <DT>Term<DD>This is the definition of the first term.
       <DT>Term<DD>This is the definition of the second term.
       </DL>

   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.

   Single occurrences of a <DT> tag without a subsequent <DD> tag are 
   allowed, and have the same significance as if the <DD> tag had been 
   present with no text.

   The opening list tag must be <DL> and must be immediately followed 
   by the first term (<DT>).

   The definition list type can take the COMPACT attribute, which 
   suggests that a compact rendering be used, because the list items 
   are small and/or the entire list is large.

   Unless you provide the COMPACT attribute, the HTML user agent may 
   leave white space between successive DT, DD pairs. The COMPACT 
   attribute may also reduce the width of the left-hand (DT) column.

   If using the COMPACT attribute, the opening list tag must be <DL 
   COMPACT>, which must be immediately followed by the first <DT> tag:

       <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>

10.6.2 Directory List

   <DIR> ... </DIR>                                             Level 0

   A Directory List element is used to present a list of items 
   containing up to 20 characters each. Items in a directory list may 
   be arranged in columns, typically 24 characters wide. If the HTML 
   user agent can optimize the column width as function of the widths 
   of individual elements, so much the better.

   A directory list must begin with the <DIR> tag which is immediately 
   followed by a <LI> (list item) tag:

       <DIR>
       <LI>A-H<LI>I-M
       <LI>M-R<LI>S-Z
       </DIR>

10.6.3 Menu List

   <MENU> ... </MENU>                                           Level 0

   A menu list is a list of items with typically one line per item. 
   The menu list style is more compact than the style of an unordered 
   list.

   A menu list must begin with a <MENU> tag which is immediately 
   followed by a <LI> (list item) tag:

       <MENU>
       <LI>First item in the list.
       <LI>Second item in the list.
       <LI>Third item in the list.
       </MENU>

10.6.4 Ordered List

   <OL> ... </OL>                                               Level 0

   The Ordered List element is used to present a numbered list of 
   items, sorted by sequence or order of importance.

   An ordered list must begin with the <OL> tag which is immediately 
   followed by a <LI> (list item) tag:

       <OL>
       <LI>Click the Web button to open the Open the URL window.
       <LI>Enter the URL number in the text field of the Open URL 
       window. The Web document you specified is displayed.
       <LI>Click highlighted text to move from one link to another.
       </OL>

   The Ordered List element can take the COMPACT attribute, which 
   suggests that a compact rendering be used.

10.6.5 Unordered List

   <UL> ... </UL>                                               Level 0

   The Unordered List element is used to present a list of items which 
   is typically separated by white space and/or marked by bullets.

   An unordered list must begin with the <UL> tag which is immediately 
   followed by a <LI> (list item) tag:

       <UL>
       <LI>First list item
       <LI>Second list item
       <LI>Third list item
       </UL>

11.  Form-based Input Elements

   Forms are created by placing input fields within paragraphs, 
   preformatted/literal text, and lists. This gives considerable 
   flexibility in designing the layout of forms.

   The following elements are used to create forms:

   FORM
       A form within a document.

   INPUT
       One input field.

   OPTION
       One option within a Select element.

   SELECT
       A selection from a finite set of options.

   TEXTAREA
       A multi-line input field.

   Each variable field is defined by an Input, Textarea, or Option 
   element and must have an NAME attribute to identify its value in 
   the data returned when the form is submitted.

   Example of use (a questionnaire form):

       <H1>Sample Questionnaire</H1>
       <P>Please fill out this questionnaire:
       <FORM METHOD="POST" ACTION="http://www.w3.org/sample">
       <P>Your name: <INPUT NAME="name" size="48">
       <P>Male <INPUT NAME="gender" TYPE=RADIO VALUE="male">
       <P>Female <INPUT NAME="gender" TYPE=RADIO VALUE="female">
       <P>Number in family: <INPUT NAME="family" TYPE=text>
       <P>Cities in which you maintain a residence:
       <UL>
       <LI>Kent <INPUT NAME="city" TYPE=checkbox VALUE="kent">
       <LI>Miami <INPUT NAME="city" TYPE=checkbox VALUE="miami">
       <LI>Other <TEXTAREA NAME="other" cols=48 rows=4></textarea>
       </UL>
       Nickname: <INPUT NAME="nickname" SIZE="42">
       <P>Thank you for responding to this questionnaire.
       <P><INPUT TYPE=SUBMIT> <INPUT TYPE=RESET>
       </FORM>

   In the example above, the <P> and <UL> tags have been used to lay 
   out the text and input fields. The HTML user agent is responsible 
   for handling which field will currently get keyboard input.

   Many platforms have existing conventions for forms, for example, 
   using Tab and Shift keys to move the keyboard focus forwards and 
   backwards between fields, and using the Enter key to submit the 
   form. In the example, the SUBMIT and RESET buttons are specified 
   explicitly with special purpose fields. The SUBMIT button is used 
   to e-mail the form or send its contents to the server as specified 
   by the ACTION attribute, while RESET resets the fields to their 
   initial values. When the form consists of a single text field, it 
   may be appropriate to leave such buttons out and rely on the Enter 
   key.

   The Input element is used for a large variety of types of input 
   fields.

   To let users enter more than one line of text, use the Textarea 
   element.

   The radio button and checkbox types of input field can be used to 
   specify multiple choice forms in which every alternative is visible 
   as part of the form. An alternative is to use the Select element 
   which is typically rendered in a more compact fashion as a pull 
   down combo list.

11.1  Form

   <FORM> ... </FORM>                                           Level 2

   The Form element is used to delimit a data input form. There can be 
   several forms in a single document, but the Form element can't be 
   nested.

   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 attribute is missing, the URL of 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.

   In general:

      o the METHOD attribute selects variations in the protocol.

      o the ENCTYPE attribute specifies the format of the submitted 
        data in case the protocol does not impose a format itself.

   The Level 2 specification defines and requires support for the HTTP 
   access protocol only.

   When the ACTION attribute is set to an HTTP URL, the METHOD 
   attribute must be set to an HTTP method [3]. The default method is 
   GET, although for many applications the POST method is preferred. 
   With the POST method, the ENCTYPE attribute is a media type 
   specifying the format of the posted data; the default is 
   "application/x-www-form-urlencoded".

   The submitted contents of the form logically consist of name/value 
   pairs. The names are usually equal to the NAME attributes of the 
   various interactive elements in the form.

       Note: The names are not guaranteed to be unique keys, nor 
       are the names of form elements required to be distinct. The 
       values encode the user's input to the corresponding 
       interactive elements. Fields with null values may be omitted 
       from the returned list of name/value pairs, whereas those 
       with non-null values should be included (even if the value 
       was not altered by the user). In particular, unselected 
       radio buttons and checkboxes should be excluded from the 
       contents list.

11.2  Input

   <INPUT>                                                      Level 2

   The Input element represents a field whose contents may be edited 
   by the user.

   Attributes of the Input element:

   ALIGN
       Vertical alignment of the image. For use only with TYPE=IMAGE. 
       The possible values are exactly the same as for the ALIGN 
       attribute of the image element.

   CHECKED
       Indicates that a checkbox or radio button is selected. 
       Unselected checkboxes and radio buttons do not return name/value 
       pairs when the form is submitted.

   MAXLENGTH
       Indicates the maximum number of characters that can be entered 
       into a text field. This can be greater than specified by the 
       SIZE attribute, in which case the field will scroll 
       appropriately. The default number of characters is unlimited.

   NAME
       Symbolic name used when transferring the form's contents. The 
       NAME attribute is required for most input types and is normally 
       used to provide a unique identifier for a field, or for a 
       logically related group of fields.

   SIZE
       Specifies the size or precision of the field according to its 
       type. For example, to specify a field with a visible width of 24 
       characters:

       INPUT TYPE=text SIZE="24"

   SRC
       A URL or URN specifying an image. For use only with TYPE=IMAGE.

   TYPE
       Defines the type of data the field accepts. Defaults to free 
       text. Several types of fields can be defined with the type 
       attribute:

       CHECKBOX
          Used for simple Boolean attributes, or for attributes that 
          can take multiple values at the same time. The latter is 
          represented by a number of checkbox fields each of which has 
          the same name. Each selected checkbox generates a separate 
          name/value pair in the submitted data, even if this results 
          in duplicate names. The default value for checkboxes is "on".

       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.

       IMAGE
          An image field upon which you can click with a pointing 
          device, causing the form to be immediately submitted. The 
          coordinates of the selected point are measured in pixel units 
          from the upper-left corner of the image, and are returned 
          (along with the other contents of the form) in two name/value 
          pairs. The x-coordinate is submitted under the name of the 
          field with ".x" appended, and the y-coordinate is submitted 
          under the name of the field with ".y" appended. Any VALUE 
          attribute is ignored. The image itself is specified by the 
          SRC attribute, exactly as for the Image element.

          Note: In a future version of the HTML specification, the 
          IMAGE functionality may be folded into an enhanced SUBMIT 
          field.

       PASSWORD
          The same as the TEXT attribute, except that text is not 
          displayed as it is entered.

       RADIO
          Used for attributes that accept a single value from a set of 
          alternatives. Each radio button field in the group should be 
          given the same name. Only the selected radio button in the 
          group generates a name/value pair in the submitted data. 
          Radio buttons require an explicit VALUE attribute.

       RESET
          A button that when pressed resets the form's fields to their 
          specified initial values. The label to be displayed on the 
          button may be specified just as for the SUBMIT button.

       SUBMIT
          A button that when pressed submits the form. You can use the 
          VALUE attribute to provide a non-editable label to be 
          displayed on the button.  The default label is application-
          specific.  If a SUBMIT button is pressed in order to submit 
          the form, and that button has a NAME attribute specified, 
          then that button contributes a name/value pair to the 
          submitted data. Otherwise, a SUBMIT button makes no 
          contribution to the submitted data.

       TEXT
          Used for a single line text entry fields. Use in conjunction 
          with the SIZE and MAXLENGTH attributes. Use the Textarea 
          element for text fields which can accept multiple lines.

   VALUE
       The initial displayed value of the field, if it displays a 
       textual or numerical value; or the value to be returned when the 
       field is selected, if it displays a Boolean value. This 
       attribute is required for radio buttons.

11.3  Option

   <OPTION>                                                     Level 2

   The Option element can only occur within a Select element. It 
   represents one choice, and can take these attributes:

   SELECTED
       Indicates that this option is initially selected.

   VALUE
       When present indicates the value to be returned if this option 
       is chosen. The returned value defaults to the contents of the 
       Option element.

   The contents of the Option element is presented to the user to 
   represent the option. It is used as a returned value if the VALUE 
   attribute is not present.

11.4  Select

   <SELECT NAME=... > ... </SELECT>                             Level 2

   The Select element allows the user to chose one of a set of 
   alternatives described by textual labels. Every alternative is 
   represented by the Option element. Attributes are:

   MULTIPLE
       The MULTIPLE attribute is needed when users are allowed to make 
       several selections, e.g. <SELECT MULTIPLE>.

   NAME
       Specifies the name that will submitted as a name/value pair.

   SIZE
       Specifies the number of visible items. If this is greater than 
       one, then the resulting form control will be a list.

   The Select element is typically rendered as a pull down or pop-up 
   list. For example:

       <SELECT NAME="flavor">
       <OPTION>Vanilla
       <OPTION>Strawberry
       <OPTION>Rum and Raisin
       <OPTION>Peach and Orange
       </SELECT>

   If no option is initially marked as selected, then the first item 
   listed is selected.

11.5  Text Area

   <TEXTAREA> ... </TEXTAREA>                                   Level 2

   The Textarea element lets users enter more than one line of text. 
   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 (</TEXTAREA>) is used to initialize the 
   field's value. This end tag is always required even if the field is 
   initially blank. When submitting a form, lines in a TEXTAREA should 
   be terminated using CRLF.

   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. HTML user agents should allow text to 
   extend beyond these limits by scrolling as needed.

       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. SGML's default (Reference Quantity Set) limits 
       the length of attribute literals to only 240 characters. The 
       HTML 2.0 SGML declaration increases the limit to 1024 
       characters.

12.  HTML Document Type Definitions

12.1  Deprecated and Recommended Sections

   Optional "deprecated" and "recommended" sections are used in the 
   HTML DTD. Conformance with this specification is defined with these 
   sections disabled. In the liberal spirit of Section 3.3, user 
   agents reading HTML documents should accept syntax corresponding to 
   the specification with "deprecated" turned on. On the other hand, 
   applications generating HTML should, in the conservative spirit, 
   generate documents that conform to the specification with the 
   "recommended" sections turned on.

12.2  Sample SGML Open Entity Catalog for HTML

   The SGML standard describes an "entity manager" as the portion or 
   component of an SGML system that maps SGML entities into the actual 
   storage model (e.g., the file system).  The standard itself does 
   not define a particular mapping methodology or notation.

   To assist the interoperability among various SGML tools and 
   systems, the SGML Open consortium has passed a technical resolution 
   that defines a format for an application-independent entity catalog 
   that maps external identifiers and/or entity names to file names.

   Each entry in the catalog associates a storage object identifier 
   (such as a file name) with information about the external entity 
   that appears in the SGML document.  In addition to entries that 
   associate public identifiers, a catalog entry can associate an 
   entity name with a storage object indentifier.  For example, the 
   following are possible catalog entries:

       PUBLIC "ISO 8879:1986//ENTITIES Added Latin 1//EN" "iso-lat1.gml"
       PUBLIC "-//ACME DTD Writers//DTD General Report//EN" report.dtd
       ENTITY "graph1" "graphics\graph1.cgm"

   In particular, the following shows entries relevant to HTML.

       -- catalog: SGML Open style entity catalog for HTML --

       -- Ways to refer to Level 2: most general to most specific --

       PUBLIC  "-//IETF//DTD HTML//EN"                 html.dtd
       PUBLIC  "-//IETF//DTD HTML 2.0//EN"             html.dtd
       PUBLIC  "-//IETF//DTD HTML Level 2//EN"         html.dtd
       PUBLIC  "-//IETF//DTD HTML 2.0 Level 2//EN"     html.dtd

       -- Ways to refer to Level 1: most general to most specific --

       PUBLIC  "-//IETF//DTD HTML Level 1//EN"         html-1.dtd
       PUBLIC  "-//IETF//DTD HTML 2.0 Level 1//EN"     html-1.dtd

       -- Ways to refer to Level 0: most general to most specific --

       PUBLIC  "-//IETF//DTD HTML Level 0//EN"         html-0.dtd
       PUBLIC  "-//IETF//DTD HTML 2.0 Level 0//EN"     html-0.dtd

       -- ISO latin 1 entity set for HTML -- 

       PUBLIC  "ISO 8879-1986//ENTITIES Added Latin 1//EN//HTML" 
                ISOlat1.sgml

12.3  SGML Declaration for HTML

   This is the SGML Declaration for HyperText Markup Language (HTML) 
   as used by the World Wide Web (WWW) application:

       <!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        150000
                      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
                       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 --
       >

12.4  HTML Level 0 DTD

   This is the Document Type Definition for the HyperText Markup 
   Language as used by minimally conforming World Wide Web 
   applications (HTML Level 0 DTD). Note that it is defined in terms 
   of the Level 2 DTD.

       <!-- html-0.dtd

            Document Type Definition for the HyperText Markup Language
            as used by minimally conforming World Wide Web applications
            (HTML Level 0 DTD).

       -->

       <!ENTITY % HTML.Version
            "-//IETF//DTD HTML 2.0 Level 0//EN"
            -- public identifier for "minimal conformance" version -- 

            -- Typical usage:

                <!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML Level 0//EN">
                <html>
                ...
                </html>
            --
            >

       <!-- Feature Test Entities -->

       <!ENTITY % HTML.Highlighting "IGNORE">
       <!ENTITY % HTML.Forms "IGNORE">

       <!ENTITY % head.extra " ">
       <!ENTITY % linkExtraAttributes " ">

       <!ENTITY % html PUBLIC "-//IETF//DTD HTML 2.0//EN">
       %html;

12.5  HTML Level 1 DTD

   This is the Document Type Definition for the HyperText Markup 
   Language with Level 1 Extensions (HTML Level 1 DTD). Note that it 
   is defined in terms of the Level 2 DTD.

       <!-- html-1.dtd

            Document Type Definition for the HyperText Markup Language
            with Level 1 Extensions (HTML Level 1 DTD).

       -->

       <!ENTITY % HTML.Version

            "-//IETF//DTD HTML 2.0 Level 1//EN"

            -- Typical usage:

                <!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML Level 1//EN">
                <html>
                ...
                </html>
            --
            >

       <!-- Feature Test Entities -->

       <!ENTITY % HTML.Forms "IGNORE">

       <!ENTITY % html PUBLIC "-//IETF//DTD HTML 2.0//EN">

       %html;

12.6  HTML Level 2 DTD

   This is the Document Type Definition for the HyperText Markup 
   Language (HTML DTD):

       <!--   html.dtd

              Document Type Definition for the HyperText Markup Language
                        (HTML DTD)

       -->

       <!ENTITY % HTML.Version
            "-//IETF//DTD HTML 2.0//EN"

            -- Typical usage:

                <!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML//EN">
                <html>
                ...
                </html>
            --
            >

       <!--============ Feature Test Entities =======================-->

       <!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
               those 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.Highlighting "INCLUDE"
            -- Use this feature test entity to validate that a
               document uses no highlighting tags, which may be
               ignored on minimal implementations.
            -->

       <!ENTITY % HTML.Forms "INCLUDE"
            -- Use this feature test entity to validate that a document
               contains no forms, which may not be supported in minimal
               implementations
            -->

       <!--============== Imported Names ============================-->

       <!ENTITY % Content-Type "CDATA"
            -- meaning an internet media type
               (aka MIME content type, as per RFC1521)
            -->

       <!ENTITY % HTTP-Method "GET | POST"
            -- as per HTTP specification, in progress
            -->

       <!ENTITY % URI "CDATA"
            -- The term URI means a CDATA attribute
               whose value is a Uniform Resource Identifier,
               as defined by "Universal Resource Identifiers"
               by Tim Berners-Lee, 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.
            -->

       <!--========= DTD "Macros" =====================-->

       <!ENTITY % heading "H1|H2|H3|H4|H5|H6">

       <!ENTITY % list " UL | OL | DIR | MENU " >

       <!--======= Character mnemonic entities =================-->

       <!ENTITY % ISOlat1 PUBLIC
         "ISO 8879-1986//ENTITIES Added Latin 1//EN//HTML">
       %ISOlat1;

       <!ENTITY amp CDATA "&#38;"     -- ampersand          -->
       <!ENTITY gt CDATA "&#62;"      -- greater than       -->
       <!ENTITY lt CDATA "&#60;"      -- less than          -->
       <!ENTITY quot CDATA "&#34;"    -- double quote       -->

       <!--====== SGML Document Access (SDA) Parameter Entities =====-->

       <!-- HTML 2.0 contains SGML Document Access (SDA) fixed
            attributes in support of easy transformation to the
            International Committee for Accessible Document Design
            (ICADD) DTD "-//EC-USA-CDA/ICADD//DTD ICADD22//EN".

            ICADD applications are designed to support usable access to
            structured information by print-impaired individuals through
            Braille, large print and voice synthesis.  For more
            information on SDA & ICADD:
               - ISO 12083:1993, Annex A.8, Facilities for Braille,
                 large print and computer voice
               - ICADD ListServ
                 <ICADD%ASUACAD.BITNET@ARIZVM1.ccit.arizona.edu>
               - Usenet news group bit.listserv.easi
               - Recording for the Blind, +1 800 221 4792
       -->

       <!ENTITY % SDAFORM  "SDAFORM  CDATA  #FIXED"
                 -- one to one mapping        -->
       <!ENTITY % SDARULE  "SDARULE  CDATA  #FIXED"
                 -- context-sensitive mapping -->
       <!ENTITY % SDAPREF  "SDAPREF  CDATA  #FIXED"
                 -- generated text prefix     -->
       <!ENTITY % SDASUFF  "SDASUFF  CDATA  #FIXED"
                 -- generated text suffix     -->
       <!ENTITY % SDASUSP  "SDASUSP  NAME   #FIXED"
                 -- suspend transform process -->

       <!--========== Text Markup =====================-->

       <![ %HTML.Highlighting [

       <!ENTITY % font " TT | B | I ">

       <!ENTITY % phrase
                  "EM | STRONG | CODE | SAMP | KBD | VAR | CITE ">

       <!ENTITY % text "#PCDATA | A | IMG | BR | %phrase | %font">

       <!ELEMENT (%font;|%phrase) - - (%text)*>
       <!ATTLIST ( TT | CODE | SAMP | KBD | VAR )
            %SDAFORM; "Lit"
            >
       <!ATTLIST ( B | STRONG )
            %SDAFORM; "B"
            >
       <!ATTLIST ( I | EM | CITE )
            %SDAFORM; "It"
            >

       <!-- <TT>       Typewriter text                         -->
       <!-- <B>        Bold text                               -->
       <!-- <I>        Italic text                             -->

       <!-- <EM>       Emphasized phrase                       -->
       <!-- <STRONG>   Strong emphais                          -->
       <!-- <CODE>     Source code phrase                      -->
       <!-- <SAMP>     Sample text or characters               -->
       <!-- <KBD>      Keyboard phrase, e.g. user input        -->
       <!-- <VAR>      Variable phrase or substituable         -->
       <!-- <CITE>     Name or title of cited work             -->

       <!ENTITY % pre.content "#PCDATA | A | HR | BR | %font | %phrase">

       ]]>

       <!ENTITY % text "#PCDATA | A | IMG | BR">

       <!ELEMENT BR    - O EMPTY>
       <!ATTLIST BR
            %SDAPREF; "&#RE;"
            >

       <!-- <BR>       Line break      -->

       <!--========= Link Markup ======================-->

       <![ %HTML.Recommended [
            <!ENTITY % linkName "ID">
       ]]>

       <!ENTITY % linkName "CDATA">

       <!ENTITY % linkType "NAMES"
            -- a list of these will be specified at a later date -->

       <!ENTITY % linkExtraAttributes
           "REL     NAMES #IMPLIED
            REV     NAMES #IMPLIED
            URN     CDATA #IMPLIED
            TITLE   CDATA #IMPLIED
           ">

       <![ %HTML.Recommended [
            <!ENTITY % A.content   "(%text)*"
            -- <H1><a name="xxx">Heading</a></H1>
                    is preferred to
               <a name="xxx"><H1>Heading</H1></a>
            -->
       ]]>

       <!ENTITY % A.content   "(%heading|%text)*">

       <!ELEMENT A     - - %A.content -(A)>
       <!ATTLIST A
            HREF %URI #IMPLIED
            NAME %linkName #IMPLIED
            %linkExtraAttributes;
            %SDAPREF; "<Anchor: #AttList>"
            >

       <!-- <A>                Anchor; source/destination of link    -->
       <!-- <A NAME="...">     Name of this anchor                   -->
       <!-- <A HREF="...">     Address of link destination           -->
       <!-- <A URN="...">      Permanent address of destination      -->
       <!-- <A REL=...>        Relationship to destination           -->
       <!-- <A REV=...>        Relationship of destination to this   -->
       <!-- <A TITLE="...">    Title of destination (advisory)       -->
       <!-- <A METHODS="...">  Operations on destination (advisory)  -->

       <!--========== Images ==========================-->

       <!ELEMENT IMG    - O EMPTY>
       <!ATTLIST IMG
            SRC %URI;  #REQUIRED
            ALT CDATA #IMPLIED
            ALIGN (top|middle|bottom) #IMPLIED
            ISMAP (ISMAP) #IMPLIED
            %SDAPREF; "<Fig><?SDATrans Img: #AttList>#AttVal(Alt)</Fig>"
            >

       <!-- <IMG>              Image; icon, glyph or illustration   -->
       <!-- <IMG SRC="...">    Address of image object              -->
       <!-- <IMG ALT="...">    Textual alternative                  -->
       <!-- <IMG ALIGN=...>    Position relative to text            -->
       <!-- <IMG ISMAP>        Each pixel can be a link             -->

       <!--========== Paragraphs=======================-->

       <!ELEMENT P     - O (%text)*>
       <!ATTLIST P
            %SDAFORM; "Para"
            >

       <!-- <P>        Paragraph       -->

       <!--========== Headings, Titles, Sections ===============-->

       <!ELEMENT HR    - O EMPTY>
       <!ATTLIST HR
            %SDAPREF; "&#RE;&#RE;"
            >

       <!-- <HR>       Horizontal rule -->

       <!ELEMENT ( %heading )  - -  (%text;)*>
       <!ATTLIST H1
            %SDAFORM; "H1"
            >
       <!ATTLIST H2
            %SDAFORM; "H2"
            >
       <!ATTLIST H3
            %SDAFORM; "H3"
            >
       <!ATTLIST H4
            %SDAFORM; "H4"
            >
       <!ATTLIST H5
            %SDAFORM; "H5"
            >
       <!ATTLIST H6
            %SDAFORM; "H6"
            >

       <!-- <H1>       Heading, level 1 -->
       <!-- <H2>       Heading, level 2 -->
       <!-- <H3>       Heading, level 3 -->
       <!-- <H4>       Heading, level 4 -->
       <!-- <H5>       Heading, level 5 -->
       <!-- <H6>       Heading, level 6 -->

       <!--========== Text Flows ======================-->

       <![ %HTML.Forms [
            <!ENTITY % block.forms "BLOCKQUOTE | FORM | ISINDEX">
       ]]>

       <!ENTITY % block.forms "BLOCKQUOTE">

       <![ %HTML.Deprecated [
            <!ENTITY % preformatted "PRE | XMP | LISTING">
       ]]>

       <!ENTITY % preformatted "PRE">

       <!ENTITY % block "P | %list | DL
               | %preformatted
               | %block.forms">

       <!ENTITY % flow "(%text|%block)*">

       <!ENTITY % pre.content "#PCDATA | A | HR | BR">
       <!ELEMENT PRE - - (%pre.content)*>
       <!ATTLIST PRE
            WIDTH NUMBER #implied
            %SDAFORM; "Lit"
            >

       <!-- <PRE>              Preformatted text               -->
       <!-- <PRE WIDTH=...>    Maximum characters per line     -->

       <![ %HTML.Deprecated [

       <!ENTITY % literal "CDATA"
            -- historical, non-conforming parsing mode where
               the only markup signal is the end tag in full
            -->

       <!ELEMENT (XMP|LISTING) - -  %literal>
       <!ATTLIST XMP
            %SDAFORM; "Lit"
            %SDAPREF; "Example:&#RE;"
            >
       <!ATTLIST LISTING
            %SDAFORM; "Lit"
            %SDAPREF; "Listing:&#RE;"
            >

       <!-- <XMP>              Example section         -->
       <!-- <LISTING>          Computer listing        -->

       <!ELEMENT PLAINTEXT - O %literal>
       <!-- <PLAINTEXT>        Plain text passage      -->
       <!ATTLIST PLAINTEXT
            %SDAFORM; "Lit"
            >

       ]]>

       <!--========== Lists ==================-->

       <!ELEMENT DL    - -  (DT | DD)+>
       <!ATTLIST DL
            COMPACT (COMPACT) #IMPLIED
            %SDAFORM; "List"
            %SDAPREF; "Definition List:"
            >

       <!ELEMENT DT    - O (%text)*>
       <!ATTLIST DT
            %SDAFORM; "Term"
            >

       <!ELEMENT DD    - O %flow>
       <!ATTLIST DD
            %SDAFORM; "LItem"
            >

       <!-- <DL>               Definition list, or glossary    -->
       <!-- <DL COMPACT>       Compact style list              -->
       <!-- <DT>               Term in definition list         -->
       <!-- <DD>               Definition of term              -->

       <!ELEMENT (OL|UL) - -  (LI)+>
       <!ATTLIST OL
            COMPACT (COMPACT) #IMPLIED
            %SDAFORM; "List"
            >
       <!ATTLIST UL
            COMPACT (COMPACT) #IMPLIED
            %SDAFORM; "List"
            >

       <!-- <UL>               Unordered list                  -->
       <!-- <UL COMPACT>       Compact list style              -->
       <!-- <OL>               Ordered, or numbered list       -->
       <!-- <OL COMPACT>       Compact list style              -->

       <!ELEMENT (DIR|MENU) - -  (LI)+ -(%block)>
       <!ATTLIST DIR
            COMPACT (COMPACT) #IMPLIED
            %SDAFORM; "List"
            %SDAPREF; "<LHead>Directory</LHead>"
            >
       <!ATTLIST MENU
            COMPACT (COMPACT) #IMPLIED
            %SDAFORM; "List"
            %SDAPREF; "<LHead>Menu</LHead>"
            >

       <!-- <DIR>              Directory list                  -->
       <!-- <DIR COMPACT>      Compact list style              -->
       <!-- <MENU>             Menu list                       -->
       <!-- <MENU COMPACT>     Compact list style              -->

       <!ELEMENT LI    - O %flow>
       <!ATTLIST LI
            %SDAFORM; "LItem"
            >

       <!-- <LI>               List item                       -->

       <!--========== Document Body ===================-->

       <![ %HTML.Recommended [
            <!ENTITY % body.content "(%heading|%block|HR|ADDRESS|IMG)*"
            -- <h1>Heading</h1>
               <p>Text ...
                    is preferred to
               <h1>Heading</h1>
               Text ...
            -->
       ]]>

       <!ENTITY % body.content "(%heading | %text | %block |
                                        HR | ADDRESS)*">

       <!ELEMENT BODY O O  %body.content>

       <!-- <BODY>     Document body   -->

       <!ELEMENT BLOCKQUOTE - - %body.content>
       <!ATTLIST BLOCKQUOTE
            %SDAFORM; "BQ"
            >

       <!-- <BLOCKQUOTE>       Quoted passage  -->

       <!ELEMENT ADDRESS - - (%text|P)*>
       <!ATTLIST  ADDRESS
            %SDAFORM; "Lit"
            %SDAPREF; "Address:&#RE;"
            >

       <!-- <ADDRESS>  Address, signature, or byline   -->

       <!--======= Forms ====================-->

       <![ %HTML.Forms [

       <!ELEMENT FORM - - %body.content
                          -(FORM) +(INPUT|SELECT|TEXTAREA)>
       <!ATTLIST FORM
            ACTION %URI #IMPLIED
            METHOD (%HTTP-Method) GET
            ENCTYPE %Content-Type; "application/x-www-form-urlencoded"
            %SDAPREF; "<Para>Form:</Para>"
            %SDASUFF; "<Para>Form End.</Para>"
            >

       <!-- <FORM>                     Fill-out or data-entry form  -->
       <!-- <FORM ACTION="...">        Address for completed form   -->
       <!-- <FORM METHOD=...>          Method of submitting form    -->
       <!-- <FORM ENCTYPE="...">       Representation of form data  -->

       <!ENTITY % InputType "(TEXT | PASSWORD | CHECKBOX |
                               RADIO | SUBMIT | RESET |
                               IMAGE | HIDDEN )">
       <!ELEMENT INPUT - O EMPTY>
       <!ATTLIST INPUT
            TYPE %InputType TEXT
            NAME CDATA #IMPLIED
            VALUE CDATA #IMPLIED
            SRC %URI #IMPLIED
            CHECKED (CHECKED) #IMPLIED
            SIZE CDATA #IMPLIED
            MAXLENGTH NUMBER #IMPLIED
            ALIGN (top|middle|bottom) #IMPLIED
            %SDAPREF; "Input: "
            >

       <!-- <INPUT>                  Form input datum                -->
       <!-- <INPUT TYPE=...>         Type of input interaction       -->
       <!-- <INPUT NAME=...>         Name of form datum              -->
       <!-- <INPUT VALUE="...">      Default/initial/selected value  -->
       <!-- <INPUT SRC="...">        Address of image                -->
       <!-- <INPUT CHECKED>          Initial state is "on"           -->
       <!-- <INPUT SIZE=...>         Field size hint                 -->
       <!-- <INPUT MAXLENGTH=...>    Data length maximum             -->
       <!-- <INPUT ALIGN=...>        Image alignment                 -->

       <!ELEMENT SELECT - - (OPTION+) -(INPUT|SELECT|TEXTAREA)>
       <!ATTLIST SELECT
            NAME CDATA #REQUIRED
            SIZE NUMBER #IMPLIED
            MULTIPLE (MULTIPLE) #IMPLIED
            %SDAFORM; "List"
            %SDAPREF;
            "<LHead>Select #AttVal(Multiple)</LHead>"
            >

       <!-- <SELECT>                   Selection of option(s)        -->
       <!-- <SELECT NAME=...>          Name of form datum            -->
       <!-- <SELECT SIZE=...>          Options displayed at a time   -->
       <!-- <SELECT MULTIPLE>          Multiple selections allowed   -->

       <!ELEMENT OPTION - O (#PCDATA)*>
       <!ATTLIST OPTION
            SELECTED (SELECTED) #IMPLIED
            VALUE CDATA #IMPLIED
            %SDAFORM; "LItem"
            %SDAPREF;
            "Option: #AttVal(Value) #AttVal(Selected)"
            >

       <!-- <OPTION>                A selection option              -->
       <!-- <OPTION SELECTED>       Initial state                   -->
       <!-- <OPTION VALUE="...">    Form datum value for this option-->

       <!ELEMENT TEXTAREA - - (#PCDATA)* -(INPUT|SELECT|TEXTAREA)>
       <!ATTLIST TEXTAREA
            NAME CDATA #REQUIRED
            ROWS NUMBER #REQUIRED
            COLS NUMBER #REQUIRED
            %SDAFORM; "Para"
            %SDAPREF; "Input Text -- #AttVal(Name): "
            >

       <!-- <TEXTAREA>                 An area for text input       -->
       <!-- <TEXTAREA NAME=...>        Name of form datum           -->
       <!-- <TEXTAREA ROWS=...>        Height of area               -->
       <!-- <TEXTAREA COLS=...>        Width of area                -->

       ]]>

       <!--======= Document Head ======================-->

       <![ %HTML.Recommended [
               <!ENTITY % head.extra "META* & LINK*">
       ]]>

       <!ENTITY % head.extra "NEXTID? & META* & LINK*">

       <!ENTITY % head.content "TITLE & ISINDEX? & BASE? &
                                (%head.extra)">

       <!ELEMENT HEAD O O  (%head.content)>

       <!-- <HEAD>     Document head   -->

       <!ELEMENT TITLE - -  (#PCDATA)*>
       <!ATTLIST TITLE
            %SDAFORM; "Ti"
            >

       <!-- <TITLE>    Title of document -->

       <!ELEMENT LINK - O EMPTY>
       <!ATTLIST LINK
            HREF %URI #REQUIRED
            %linkExtraAttributes;
            %SDAPREF; "Linked to : #AttVal (TITLE) (URN) (HREF)>"
            >

       <!-- <LINK>               Link from this document             -->
       <!-- <LINK HREF="...">    Address of link destination         -->
       <!-- <LINK URN="...">     Lasting name of destination         -->
       <!-- <LINK REL=...>       Relationship to destination         -->
       <!-- <LINK REV=...>       Relationship of destination to this -->
       <!-- <LINK TITLE="...">   Title of destination (advisory)     -->
       <!-- <LINK METHODS="..."> Operations allowed (advisory)       -->

       <!ELEMENT ISINDEX - O EMPTY>
       <!ATTLIST ISINDEX
            %SDAPREF;
            "<Para>[Document is indexed/searchable.]</Para>"
            >

       <!-- <ISINDEX>          Document is a searchable index       -->

       <!ELEMENT BASE - O EMPTY>
       <!ATTLIST BASE
            HREF %URI; #REQUIRED
            >

       <!-- <BASE>             Base context document                -->
       <!-- <BASE HREF="...">  Address for this document            -->

       <!ELEMENT NEXTID - O EMPTY>
       <!ATTLIST NEXTID
            N %linkName #REQUIRED
            >

       <!-- <NEXTID>           Next ID to use for link name         -->
       <!-- <NEXTID N=...>     Next ID to use for link name         -->

       <!ELEMENT META - O EMPTY>
       <!ATTLIST META
            HTTP-EQUIV  NAME    #IMPLIED
            NAME        NAME    #IMPLIED
            CONTENT     CDATA   #REQUIRED
            >

       <!-- <META>                     Generic Metainformation      -->
       <!-- <META HTTP-EQUIV=...>      HTTP response header name    -->
       <!-- <META NAME=...>            Metainformation name         -->
       <!-- <META CONTENT="...">       Associated information       -->

       <!--======= Document Structure =================-->

       <![ %HTML.Deprecated [
            <!ENTITY % html.content "HEAD, BODY, PLAINTEXT?">
       ]]>
       <!ENTITY % html.content "HEAD, BODY">

       <!ELEMENT HTML O O  (%html.content)>

       <!ENTITY % version.attr "VERSION CDATA #FIXED '%HTML.Version;'">

       <!ATTLIST HTML
            %version.attr;
            %SDAFORM; "Book"
            >

       <!-- <HTML>                     HTML Document   -->

13.  Character Sets and Entity Sets

   The HTML DTD includes some entities from the entity sets in the
   appendixes of the SGML standard. The SGML declaration for HTML
   refers to the ISO-8859-1 character set.

13.1  Numeric and Special Graphic Entity Set

   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 Standard 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.

       GLYPH     NAME        SYNTAX       DESCRIPTION
       <         lt          &lt;         Less than sign
       >         gt          &gt;         Greater than sign
       &         amp         &amp;        Ampersand
       "         quot        &quot;       Double quote sign

13.2  Added Latin 1 Entity Set

   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 Standard 
   8879:1986//ENTITIES Added Latin 1//EN. HTML supports 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)
       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
       aring     &aring;     Small a, ring
       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
       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


13.3  ISO-8859-1 Character Set

   Each character in the document character set can be written as a
   numeric character reference. This list, sorted numerically, is
   derived from 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 sign
       &#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
       &#94;                 Caret
       &#95;                 Horizontal bar (underscore)
       &#96;                 Acute accent

       &#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, grave accent
       &#193;                Capital A, acute accent
       &#194;                Capital A, circumflex accent
       &#195;                Capital A, tilde
       &#196;                Capital A, dieresis or umlaut mark
       &#197;                Capital A, ring
       &#198;                Capital AE dipthong (ligature)
       &#199;                Capital C, cedilla
       &#200;                Capital E, grave accent
       &#201;                Capital E, acute accent
       &#202;                Capital E, circumflex accent
       &#203;                Capital E, dieresis or umlaut mark
       &#204;                Capital I, grave accent
       &#205;                Capital I, acute accent
       &#206;                Capital I, circumflex accent
       &#207;                Capital I, dieresis or umlaut mark
       &#208;                Capital Eth, Icelandic
       &#209;                Capital N, tilde
       &#210;                Capital O, grave accent
       &#211;                Capital O, acute 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, grave accent
       &#218;                Capital U, acute 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, grave accent
       &#225;                Small a, acute accent
       &#226;                Small a, circumflex accent
       &#227;                Small a, tilde
       &#228;                Small a, dieresis or umlaut mark
       &#229;                Small a, ring
       &#230;                Small ae dipthong (ligature)
       &#231;                Small c, cedilla
       &#232;                Small e, grave accent
       &#233;                Small e, acute accent
       &#234;                Small e, circumflex accent
       &#235;                Small e, dieresis or umlaut mark
       &#236;                Small i, grave accent
       &#237;                Small i, acute accent
       &#238;                Small i, circumflex accent
       &#239;                Small i, dieresis or umlaut mark
       &#240;                Small eth, Icelandic
       &#241;                Small n, tilde
       &#242;                Small o, grave accent
       &#243;                Small o, acute 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, grave accent
       &#250;                Small u, acute 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

14.  Security Considerations

   Anchors, embedded images, and all other elements which contain URIs 
   as parameters may cause the URI to be dereferenced in response to 
   user input. 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.

15.  References

   [1]  T. Berners-Lee. "Universal Resource Identifiers in WWW: A 
        Unifying Syntax for the Expression of Names and Addresses of 
        Objects on the Network as used in the World-Wide Web."
        RFC 1630, CERN, June 1994.

   [2]  T. Berners-Lee, L. Masinter, and M. McCahill. "Uniform Resource 
        Locators (URL)." RFC 1738, CERN, Xerox PARC, University of 
        Minnesota, October 1994.

   [3]  T. Berners-Lee, R. T. Fielding, and H. Frystyk Nielsen. 
        "Hypertext Transfer Protocol -- HTTP/1.0." Work in Progress 
        (draft-ietf-http-v10-spec-00.ps), MIT, UC Irvine, CERN,
        March 1995.

   [4]  N. Borenstein and N. Freed. "MIME (Multipurpose Internet Mail 
        Extensions) Part One: Mechanisms for Specifying and Describing 
        the Format of Internet Message Bodies." RFC 1521, Bellcore, 
        Innosoft, September 1993.

   [5]  R. T. Fielding. "Relative Uniform Resource Locators." Work in 
        Progress (draft-ietf-uri-relative-url-06.txt), UC Irvine,
        March 1995.

   [6]  C. F. Goldfarb. "The SGML Handbook." Y. Rubinsky, Ed., Oxford 
        University Press, 1990.

   [7]  J. Postel. "Media Type Registration Procedure." RFC 1590, 
        USC/ISI, March 1994.

   [8]  J. Reynolds and J. Postel. "Assigned Numbers." STD 2, RFC 1700, 
        USC/ISI, October 1994.

   [9]  SoftQuad. "The SGML Primer." 3rd ed., SoftQuad Inc., 1991.

   [10] US-ASCII. Coded Character Set - 7-Bit American Standard Code 
        for Information Interchange. Standard ANSI X3.4-1986, ANSI, 
        1986.

   [11] ISO 8859. International Standard -- Information Processing --
        8-bit Single-Byte Coded Graphic Character Sets -- Part 1: Latin 
        Alphabet No. 1, ISO 8859-1:1987. Part 2: Latin alphabet No. 2, 
        ISO 8859-2, 1987. Part 3: Latin alphabet No. 3, ISO 8859-3, 
        1988. Part 4: Latin alphabet No. 4, ISO 8859-4, 1988. Part 5: 
        Latin/Cyrillic alphabet, ISO 8859-5, 1988. Part 6: Latin/Arabic 
        alphabet, ISO 8859-6, 1987. Part 7: Latin/Greek alphabet, ISO 
        8859-7, 1987. Part 8: Latin/Hebrew alphabet, ISO 8859-8, 1988. 
        Part 9: Latin alphabet No. 5, ISO 8859-9, 1990.

   [12] ISO 8879. Information Processing -- Text and Office Systems -- 
        Standard Generalized Markup Language (SGML), 1986.

16.  Acknowledgments

   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, which has included the 
   addition of in-line images introduced by the NCSA Mosaic software 
   for WWW. Dave Raggett played an important role in deriving the 
   FORMS material from the HTML+ specification.

   Dan Connolly and Karen Olson Muldrow rewrote the HTML Specification 
   in 1994. The document was then edited by the HTML working group as 
   a whole, with updates being made by Eric Schieler, Mike Knezovich, 
   and Eric W. Sink at Spyglass, Inc. Finally, Roy Fielding 
   restructured the entire draft into its current form.

   Special thanks to the many people who have contributed to this 
   specification:

       Terry Allen                        Marc Andreessen
       Tim Berners-Lee                    Paul Burchard
       James Clark                        Daniel W. Connolly
       Roy T. Fielding                    Peter Flynn
       Jay Glicksman                      Paul Grosso
       Eduardo Gutentag                   Bill Hefley
       Chung-Jen Ho                       Mike Knezovich
       Tom Magliery                       Murray Maloney
       Larry Masinter                     Karen Olson Muldrow
       Bill Perry                         Dave Raggett
       E. Corprew Reed                    Yuri Rubinsky
       Eric Schieler                      James L. Seidman
       Eric W. Sink                       Stuart Weibel
       Chris Wilson                       Francois Yergeau

17.  Authors' Addresses

   Tim Berners-Lee
   Director, W3 Consortium
   MIT Laboratory for Computer Science
   545 Technology Square
   Cambridge, MA 02139, U.S.A.
   Tel: +1 (617) 253 9670
   Fax: +1 (617) 258 8682
   Email: timbl@w3.org

   Daniel W. Connolly
   Research Technical Staff, W3 Consortium
   MIT Laboratory for Computer Science
   545 Technology Square
   Cambridge, MA 02139, U.S.A.
   Fax: +1 (617) 258 8682
   Email: connolly@w3.org
   URL: http://www.w3.org/hypertext/WWW/People/Connolly/


Appendices

   These appendices are provided for informational reasons only -- they 
   do not form a part of the HTML specification.

A.  Obsolete Features

   This section describes elements that are no longer part of HTML. 
   User agent implementors should implement these obsolete elements for 
   compatibility with previous versions of the HTML specification.

A.1  Comment Element

   The Comment element is used to delimit unneeded text and comments. 
   The Comment element has been introduced in some HTML applications 
   but should be replaced by the SGML comment feature in new HTML 
   user agents (see Section 2.2.5).

A.2  Highlighted Phrase Element

   <HP>

   The Highlighted Phrase element should be ignored if not 
   implemented. This element has been replaced by more meaningful 
   elements (see Section 8).

   Example of use:

       <HP1>first highlighted phrase</HP1>non-highlighted 
       text<HP2>second highlighted phrase</HP2> etc.

A.3  Plain Text Element

   <PLAINTEXT>

   The Plain Text element is used to terminates the HTML entity and to 
   indicate that what follows is not SGML which does not require 
   parsing. Instead, an old HTTP convention specified that what 
   followed was an ASCII (MIME "text/plain") body. Its presence is an 
   optimization. There is no closing tag.

   Example of use:

       <PLAINTEXT>
       0001 This is line one of a long listing
       0002 file from <ANY@HOST.INC.COM> which is sent

A.4  Example and Listing Elements

   <XMP> ... </XMP> and <LISTING> ... </LISTING>

   The Example and Listing elements have been replaced by the 
   Preformatted Text element (Section 10.2).

   These styles allow text of fixed-width characters to be embedded 
   absolutely as is into the document. The syntax is:

       <LISTING> ... </LISTING>

   or

       <XMP> ... </XMP>

   The text between these tags is typically rendered in a monospaced 
   font so that any formatting done by character spacing on successive 
   lines will be maintained.

   Between the opening and closing tags:

      o The text may contain any ISO Latin-1 printable characters, 
        expect for the end tag opener. The Example and Listing elements 
        have historically used specifications which do not conform to 
        SGML. Specifically, the text may contain ISO Latin printable 
        characters, including the tag opener, as long it they does not 
        contain the closing tag in full.

      o SGML does not support this form. HTML user agents may vary on 
        how they interpret other tags within Example and Listing 
        elements.

      o Line boundaries within the text are rendered as a move to the 
        beginning of the next line, except for one immediately 
        following a start tag or immediately preceding an end tag.

      o The horizontal tab character must be interpreted as the 
        smallest positive nonzero number of spaces which will leave the 
        number of characters so far on the line as a multiple of 8. Its 
        use is not recommended.

   The Listing element is rendered so that at least 132 characters fit 
   on a line. The Example element is rendered to that at least 80 
   characters fit on a line but is otherwise identical to the Listing 
   element.

B.  Proposed Features

   This section describes proposed HTML elements and entities that are 
   not currently supported under HTML Levels 0, 1, or 2, but may be 
   supported in the future.

B.1  Additional Character Entities

   To indicate special characters, HTML uses entity or numeric 
   representations. Additional character presentations are proposed:

       CHARACTER                          REPRESENTATION
       Non-breaking space                 &nbsp;
       Soft-hyphen                        &shy;
       Registered                         &reg;
       Copyright                          &copy;

B.2  Defining Instance Element

   <DFN> ... </DFN>

   The Defining Instance element indicates the defining instance of a 
   term. The typical rendering is bold or bold italic. This element is 
   not widely supported.

B.3  Strike Element

   <STRIKE> ... </STRIKE>

   The Strike element is proposed to indicate strikethrough, a font 
   style in which a horizontal line appears through characters. This 
   element is not widely supported.

B.4  Underline Element

   <U> ... </U>

   The Underline element is proposed to indicate that the text should 
   be rendered as underlined. This proposed tag is not supported by 
   all HTML user agents.

   Example of use:

       The text <U>shown here</U> is rendered in the document as 
       underlined.