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Versions: 00 01 02 03 04 05 rfc1866                                     
HTML Working Group                                         T. Berners-Lee
INTERNET-DRAFT                                                    MIT/W3C
<draft-ietf-html-spec-03.txt>                                 D. Connolly
Expires: In six months                                       May 31, 1995


                   Hypertext Markup Language - 2.0


                               CONTENTS


     1.  Introduction
     2.  HTML as an Application of SGML
     3.  HTML as an Internet Media Type
     4.  Document Structure
     5.  Character, Words, and Paragraphs
     6.  Hyperlinks
     7.  Forms
     8.  HTML Public Text
     9.  Glossary
     10.  Bibliography
     11.  Appendices
     12.  Acknowledgments



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>.

In this draft, the first three sections are considered essentially
finished. Sections 4 and 5 have been significantly revised and are
open to comments, though I'm fairly happy with those parts. Section 6
is somewhat new: it collects all information about hyperlinking into
one place. Sections 7 (forms elements) has also been revised, and
there are a few points I'm not sure on. The glossary (section 8) has
also been tweaked. Section 8 ``public text'' has been stable for some
time, but as it's critical, I'd appreciate a careful review just the
same.


                          ABSTRACT

     The Hypertext Markup Language (HTML) is a simple markup
     language used to create hypertext documents that are
     platform independent. HTML documents are SGML documents with
     generic semantics that are appropriate for representing
     information from a wide range of domains. HTML markup can
     represent hypertext news, mail, documentation, and
     hypermedia; menus of options; database query results; simple
     structured documents with in-lined graphics; and hypertext
     views of existing bodies of information.

     HTML has been in use by the World Wide Web (WWW) global
     information initiative since 1990. This specification
     roughly corresponds to the capabilities of HTML in common
     use prior to June 1994. HTML is 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.


1. Introduction

     The HyperText Markup Language (HTML) is a simple data format
     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 domains.


1.1. Scope

     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''.

     HTML is an application of ISO Standard 8879:1986
     _Information Processing Text and Office Systems; Standard
     Generalized Markup Language_ (SGML). The HTML Document Type
     Definition (DTD) is a formal definition of the HTML syntax
     in terms of SGML.

     This specification also defines HTML as an Internet Media
     Type[IMEDIA] and MIME Content Type[MIME] 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. Conformance

     This specification governs the syntax of HTML documents and
     the behaviour of HTML user agents.


1.2.1. Documents

     A document is a conforming HTML document only if:

          * It is a conforming SGML document, and it conforms to
          the HTML DTD (see 8.1, "HTML DTD").

          NOTE - There are a number of syntactic idioms that are
          not supported or are supported inconsistently in some
          historical user agent implementations. These idioms are
          called out in notes like this throughout this
          specification.
          HTML documents should not contain these idioms, at
          least until such time as support for them is widely
          deployed.

          * It conforms to the application conventions in this
          specification. For example, the value of the HREF
          attribute of the <A> element must conform to the URI
          syntax.

          * Its document character set includes ANSI/ISO 8859-1
          and agrees with ISO/IEC 10646-1; that is, each code
          position listed in 11.1, "The ANSI/ISO 8859-1 Coded
          Character Set" is included, and each code position in
          the document character set is mapped to the same
          character as ISO10646 designates for that code
          position.

          NOTE - The document character set is somewhat
          independent of the character encoding scheme used to
          represent a document. For example, the ISO-2022-JP
          character encoding scheme can be used for HTML
          documents, since its repertoire is a subset of the
          ISO10646 repertoire. The critical distinction is that
          numeric character references agree with ISO10646
          regardless of how the document is encoded.

     The HTML DTD defines a standard HTML document type and
     several variations, based on feature test entities:


     HTML.Recommended
                    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.

                    For example, in order to preserve the structure of
                    a document, an editing user agent may translate
                    HTML documents to the recommended subset, or it
                    may require that the documents be in the
                    recommended subset for import.

     HTML.Deprecated
                    Certain features of the language are necessary for
                    compatibility with earlier versions of the
                    specification, but they tend to be used and
                    implemented inconsistently, and their use is
                    deprecated. This feature test entity enables a
                    document type definition that eliminates these
                    features.

                    Documents generated by tranlation software or
                    editing software should not contain these idioms.


1.2.2. User Agents

     An HTML user agent conforms to this specification if:

          * It parses the characters of an HTML document into
          data characters and markup according to [SGML].

          NOTE - In the interest of robustness and extensibility,
          there are a number of widely deployed conventions for
          handling non-conforming documents. See 3.2.1,
          "Undeclared Markup Error Handling" for details.

          * It supports the `ISO-8859-1' character encoding
          scheme and processes each character in the ISO Latin
          Alphabet No. 1 as specified in 5.1, "The ISO Latin 1
          Character Repertoire".

          NOTE - To support non-western writing systems, HTML
          user agents should support ISO-10646-UCS-2 or similar
          character encoding schemes and as much of the character
          repertoire of ISO10646 as is practical.

          * It behaves identically for documents whose parsed
          token sequences are identical.
          For example, comments and the whitespace in tags
          disappear during tokenization, and hence they do not
          influence the behaviour of conforming user agents.

          * It allows the user to traverse (or at least attempt
          to traverse, resources permitting) all hyperlinks in an
          HTML document.

          * It allows the user to express all form field values
          specified in an HTML document and to (attempt to)
          submit the values as requests to information services.


2. HTML as an Application of SGML

     HTML is an application of ISO 8879:1986 -- Standard
     Generalized Markup Language (SGML). SGML is a system for
     defining structured document types and markup languages to
     represent instances of those document types[SGML]. The
     public text -- DTD and SGML declaration -- of the HTML
     document type definition are provided in 8, "HTML Public
     Text".

     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 sequence of
     characters organized physically into a set of entities, and
     logically as a hierarchy of elements.

     The first production of the SGML 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 that occur
     in all text entities in the document, and the code positions
     associated with those characters.

     The SGML declaration also specifies the syntax-reference
     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 the sequence of
     characters of the document 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></p>

     An HTML user agent should use the SGML declaration that is
     given in 8.2, "SGML Declaration for HTML". According to its
     document character set, `&#42;' refers to an asterisk
     character.

     The instance above is regarded as the following sequence of
     terminals:

          1. TITLE start-tag

          2. data characters: ``Parsing Example''

          3. TITLE end-tag

          4. P start-tag

          5. data characters ``Some text. ''

          6. EM start-tag

          7. ``*wow*''

          8. EM end-tag

          9. P 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' (8.1, "HTML DTD"). Hence the
     terminals above parse as:

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


2.2. HTML Lexical Syntax

     SGML specifies an abstract syntax and a reference concrete
     syntax. Aside from certain quantities and capacities (e.g.
     the limit on the length of a name), all HTML documents use
     the reference concrete syntax. In particular, all markup
     characters are in the repertoire of ISO 646 IRV. Data
     characters are drawn from the document character set (see 5,
     "Character, Words, and Paragraphs").

     A complete discussion of SGML parsing, e.g. the mapping of a
     sequence of characters to a sequence of tags and data, is
     left to the SGML standard[SGML]. This section is only a
     summary.


2.2.1. Data Characters

     Any sequence of characters that do not constitute markup
     (see 9.6 ``Delimiter Recognition'' of [SGML]) 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 digit:

     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 mechanisms, 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 conflict with
          techniques for reducing HTML to 7 bit ASCII for
          transport, they are not used in this version of the
          HTML DTD.


2.2.2. Tags

     Tags delimit elements such as 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 data character
     strings 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, 8.1, "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.


2.2.3. 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 `<'.


2.2.4. 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, though some attributes may be just a
     value. White space is allowed around the equal sign.

     The value of the attribute may be either:

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

          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. For
          example, `<IMG SRC="eq1.jpg" alt="a>b">' should be
          written `<IMG SRC="eq1.jpg" alt="a&#62;b">' or `<IMG
          SRC="eq1.jpg" alt="a&gt;b">'.

          * A name token (a sequence of letters, digits, periods,
          or hyphens).

          NOTE - Some historical implementations allow any
          character except space or `>' in a name token.

     In this example, <img> is the element name, src is the
     attribute name, and `http://host/dir/file.gif' is the
     attribute value:

     <img src='http://host/dir/file.gif'>

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

     Attributes 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, use a comment
     declaration. A comment declaration consists of `<!' followed
     by zero or more comments followed by `>'. Each comment
     starts with `--' and includes all text up to and including
     the next occurrence of `--'. In a comment declaration, white
     space is allowed after each comment, but not before the
     first comment. The entire comment declaration is ignored.

          NOTE - Some historical HTML implementations incorrectly
          consider any `>' character to be the termination of a
          comment.

     For example:

     <HEAD>
     <TITLE>HTML Comment Example</TITLE>
     <!-- Id: html-sgml.sgm,v 1.5 1995/05/26 21:29:50 connolly Exp  -->
     <!-- another -- -- comment -->
     <!>
     </HEAD>
     <BODY>
     <p> <!- not a comment, just regular old data characters ->


2.2.6. 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 1
     documents. HTML user agents should be able to preserve all
     formatting distinctions represented in an HTML 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). Conforming
     HTML user agents should support form entry and submission.


3.1. text/html media type

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

     Media Type name
                    text

     Media subtype
     name
                    html

     Required
     parameters
                    none

     Optional
     parameters
                    level, charset

     Encoding
     considerations
                    any encoding is allowed

     Security
     considerations
                    see 3.3, "Security Considerations"

     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. Level 1 is all
                    features defined in this specification except
                    those that require the <FORM> element. Level 2
                    includes form processing. Level 2 is the default.

     Charset
                    The charset parameter (as defined in section 7.1.1
                    of RFC 1521[MIME]) may be given to specify the
                    character encoding scheme 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 scheme. The text
     entity consists of the characters determined by this
     character encoding scheme and the octets of the body of the
     message entity.


3.2.1. Undeclared Markup Error Handling

     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 are warned that this convention is not
     binding: unspecified behavior may result, as such markup is
     not conforming to this specification.


3.2.2. 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 (code positions 10 and 13
     respectively) (section 7.6.1, ``Record Boundaries'' in
     [SGML]).

     [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 a CR LF
     sequence. 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 treat any of the three common representations
     of end-of-line as starting a new line.


3.3. 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.

     The widely deployed methods for submitting forms requests --
     HTTP and SMTP -- provide little assurance of
     confidentiality. Information providers who request sensitive
     information via forms -- especially by way of the `PASSWORD'
     type input field (see 7.1.2, "Input Field: INPUT") -- should
     be aware and make their users aware of the lack of
     confidentiality.


4. Document Structure

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

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

          NOTE - If the body of a `text/html' message entity 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 and the following document type
     declarations:

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

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


4.1. Document Element: <HTML>

     The HTML document element consists of a head and a body,
     much like a memo or a mail message. The head contains the
     title and other optional elements. The body is a text flow
     consisting of paragraphs, lists, and other elements.


4.2. Head: <HEAD>

     The head of an HTML document is an unordered collection of
     information about the document. For example:

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


4.2.1. Title: <TITLE>

     Every HTML document must contain a <TITLE> element.

     The title should identify the contents of the document in a
     global context. A short title, such as ``Introduction'' may
     be meaningless out of context. A title such as
     ``Introduction to HTML Elements'' is more appropriate.

          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.

     A user agent may display the title of a document in a
     history list or as a label for the window displaying the
     document. Contrast with headings (4.4, "Headings: H1 ...
     H6"), which are typically displayed with the body text flow.


4.2.2. Base URI: <BASE>

     The optional <BASE> element specifies the URI of the
     document, overriding any context otherwise known to the user
     agent. The required HREF attribute specifies the URI for
     navigating the document (see 6, "Hyperlinks"). The value of
     the HREF attribute must be an absolute URI.


4.2.3. Keyword Index: <ISINDEX>

     The <ISINDEX> element indicates that the user agent should
     allow the user to search an index by giving keywords. See
     6.3, "Queries and Indexes" for details.


4.2.4. Link: <LINK>

     The <LINK> element represents a hyperlink. It is typically
     used to indicate authorship, related indexes and glossaries,
     older or more recent versions, stylesheets, document
     hierarchy etc.


4.2.5. Associated Metainformation: <META>

     The <META> element is an extensible container for use in
     identifying, indexing, and cataloging specialized document
     metainformation. Metainformation has two main functions:

          * to provide a means to discover that the data set
          exists and how it might be obtained or accessed; and

          * to document the content, quality, and features of a
          data set and so give an indication of its fitness for
          use.

     Each <META> element specifies a name/value pair. 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.

          NOTE - The <META> element should not be used where a
          specific element such as <TITLE> would be appropriate.

     HTTP servers should read the content of the document <HEAD>
     to generate header fields corresponding to any elements
     defining a value for the attribute HTTP-EQUIV.

          NOTE - The method by which the server extracts document
          metainformation is unspecified and not mandatory. 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. An HTTP server may use this information to
                    process the doducment. In particular, it should
                    include a header field in the responses to GET
                    requests for this document: the header name is
                    taken from the HTTP-EQUIV attribute value, and the
                    header value is taken from the value of the
                    CONTENT attribute. HTTP header names are not case
                    sensitive.

     NAME
                    name of the name/value pair. If not present,
                    HTTP-EQUIV gives the name.

     CONTENT
                    The value of the name/value pair.

     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 should include the following header fields:

     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.,

     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.


4.2.6. Next Id: <NEXTID>

     They <NEXTID> element gives a hint for the name to use for
     an <A> element when editing an HTML document. It should be
     distinct from all NAME attribute values on <A> elements. For
     example:

     <NEXTID N=Z27>


4.3. Body: <BODY>

     The <BODY> element contains the text flow of the document,
     including headings, paragraphs, lists, etc.

     For example:

     <BODY>
     <h1>Important Stuff</h1>
     <p>Explanation about important stuff...
     </BODY>


4.4. Headings: <H1> ... <H6>

     The six heading elements, <H1> through <H6>, denote section
     headings. Although the order and occurence of headings is
     not constrained by the HTML DTD, documents should not skip
     levels (for example, from H1 to H3), as converting such
     documents to other representations is often problematic.

     Example of use:

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

     Typical renderings are:

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

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

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

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

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

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


4.5. Block Structuring Elements

     Each of the following elements defines a block structure;
     that is, they indicate a paragraph break before and after.


4.5.1. Paragraph: <P>

     The <P> element indicates a paragraph. The exact
     indentation, leading space, etc. of a paragraph is not
     specified 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. The first line in a paragraph is
     indented in some cases.

     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>


4.5.2. Preformatted Text: <PRE>

     The <PRE> element represents a character cell block of
     textand so is suitable for text that has been formatted on
     screen.

     The <PRE> tag may be used with the optional WIDTH attribute.
     The WIDTH attribute specifies the maximum number of
     characters for a line and allows the HTML user agent to
     select a suitable font and indentation.

     Within preformatted text:

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

          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.

          * Anchor elements and phrase markup may be used.

          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
          phrase markup.

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

          NOTE - Som historical documents contain <P> tags in
          <PRE> elements. User agents are engcouraged to treat
          this a a line break. A <P> tag followed by a newline
          character should produce only one line break, not a
          line break plus a blank line.

          * 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.

     Example of use:

     <PRE>
     This is an example line.
     </PRE>


4.5.3. Address: <ADDRESS>

     The <ADDRESS> element specifies such information as address,
     signature and authorship, often at the beginning or end of
     the body of a document.

     Typically, the <ADDRESS> element is rendered in an italic
     typeface and may be indented.

     Example of use:

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


4.5.4. Block Quote: <BLOCKQUOTE>

     The <BLOCKQUOTE> element contains text quoted from another
     source.

     A typical rendering might be a slight extra left and right
     indent, and/or italic font. The <BLOCKQUOTE> 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.


4.6. List Elements

     HTML includes a number of list elements. They may be used in
     combination; for example, a <OL> may be nested in an <LI>
     element of a <UL>.


4.6.1. Unordered List: <UL>, <LI>

     The <UL> represents a list of items with no inherent
     ordering -- typically a bulleted list.

     The content of a <UL> element is a sequence of <LI>
     elements. For example:

     <UL>
     <LI>First list item
     <LI>Second list item
      <p>second paragraph of second item
     <LI>Third list item
     </UL>


4.6.2. Ordered List: <OL>

     The <UL> element represents an ordered list of items, sorted
     by sequence or order of importance.

     The content of a <OL> element is a sequence of <LI>
     elements. For example:

     <OL>
     <LI>Click the Web button to open the Open the URI window.
     <LI>Enter the URI number in the text field of the Open URI
     window. The Web document you specified is displayed.
       <ol>
        <li>substep 1
        <li>substep 2
       </ol>
     <LI>Click highlighted text to move from one link to another.
     </OL>

     The COMPACT attribute suggests that a compact rendering be
     used.


4.6.3. Directory List: <DIR>

     The <DIR> element is similar to the <UL> element. It
     represents a list of short items, typically up to 20
     characters each. Items in a directory list may be arranged
     in columns, typically 24 characters wide.

     The content of a <OL> element is a sequence of <LI>
     elements. Nested block elements are not allowed in the
     content of <DIR> elements. For example:

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


4.6.4. Menu List: <MENU>

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

     The content of a <MENU> element is a sequence of <LI>
     elements. Nested block elements are not allowed in the
     content of <MENU> elements. For example:

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


4.6.5. Definition List: <DL>, <DT>, <DD>

     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.

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

     Unless the COMPACT attribute is present, an 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.

     <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>


4.7. Phrase Markup

     Phrases may be marked up according to idiomatic usage,
     typographic appearance, or for use as hyperlink anchors.

     User agents must render highlighted phrases 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.

     Phrase elements may be nested within the content of other
     phrase elements; however, HTML user agents may render nested
     phrase elements indistinctly from non-nested elements:

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


4.7.1. Idiomatic Elements


4.7.1.1. Citation: <CITE>

     The <CITE> element is used to indicate the title of a book
     or other citation. It is typically typeset as italics. For
     example:

     He just couldn't get enough of <cite>The Grapes of Wrath</cite>.


4.7.1.2. Code: <CODE>

     The <CODE> element indicates an example of code, typically
     rendered in a monospaced font. Contrast with the <PRE> block
     structuring element in 4.5.2, "Preformatted Text: PRE". For
     example:

     The expression <code>x += 1</code> is short for <code>x = x + 1</code>.


4.7.1.3. Emphasis: <EM>

     The <EM> element indicates an emphasized phrase, typically
     rendered as italics. For example:

     A singular subject <em>always</em> takes a singular verb.


4.7.1.4. Keyboard: <KBD>

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

     Enter <kbd>FIND IT</kbd> to search the database.


4.7.1.5. Sample: <SAMP>

     The <SAMP> element indicates a sequence of literal
     characters, typically rendered in a monospaced font. For
     example:

     The only word containing the letters <samp>mt</samp> is dreamt.


4.7.1.6. Strong Empasis: <STRONG>

     The <STRONG> element indicates strong emphasis, typically
     rendered in bold. For example:

     <strong>STOP</strong>, or I'll say "<strong>STOP</strong>" again!.


4.7.1.7. Variable: <VAR>

     The <VAR> element indicates a placeholder, typically
     rendered as italic. For example:

     Take a guess: Roses are <var>blank</var>.


4.7.2. Typographic Elements

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

     Typical renderings for idomatic elements vary between user
     agents. If a specific rendering is necessary -- for example,
     when referring to a specific text attribute as in ``The
     italic parts are mandatory'' -- a typographic element can be
     used to ensure that the intended typography is used where
     possible.


4.7.2.1. Bold: <B>

     The <B> element indicated bold text. Where bold typography
     is unavailable, an alternative representation may be used.


4.7.2.2. Italic: <I>

     The <I> element indicated italic text. Where italic
     typography is unavailable, an alternative representation may
     be used.


4.7.2.3. Typewriter: <TT>

     The <TT> element indicates typewriter text. Where a
     typewriter font is unavailable, an alternative
     representation may be used.


4.7.3. Anchor: <A>

     The <A> element indicates the source and/or destination of a
     hyperlink (see 6, "Hyperlinks"). At least one of the NAME
     and HREF attributes should be given. Attributes of the <A>
     element:

     HREF
                    gives the destination of a hyperlink.

     NAME
                    gives the name of the anchor, and makes it
                    available as a navigation destination.

     TITLE
                    suggests a title for the destination resource --
                    advisory only. The TITLE attribute may be used:

          * for display prior to accessing the destination
          resource, 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;

          * for resources that do not specify a title such as
          graphics, plain text and Gopher menus, for use as a
          window title.

     REL
                    The REL attribute gives the relationship(s)
                    described by the hyperlink. The value is a
                    whitespace separated list of relationship names.

     REV
                    same as the REL attribute, but the semantics of
                    the relationship 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.

     URN
                    specifies a preferred, more persistent identifier
                    for the destination. The format of URNs is under
                    discussion (1995) by various working groups of the
                    Internet Engineering Task Force.

     METHODS
                    specifies methods to be used in accessing the
                    destination, as a whitespace-separated list of
                    names. For similar reasons as for the TITLE
                    attribute, it may 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.


4.8. Line Break: <BR>

     The <BR> element specifies a line break between words (see
     5, "Character, Words, and Paragraphs"). For example:

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


4.9. Horizontal Rule: <HR>

     The <HR> element is a divider between sections of text;
     typcially a full width horizontal rule or equivalent
     graphic. For example:

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


4.10. Image: <IMG>

     The <IMG> element refers to an image or icon.

     HTML user agents that cannot process images ignore the <IMG>
     element unless it the ALT attribute is present.

          NOTE - Some HTML user agents can process graphics
          linked via anchors , but not <IMG> graphics. If a
          graphic is essential, it should be referenced from an
          <A> element rather than in <IMG> element.If the graphic
          is not essential, then the <IMG> element is
          appropriate.

     Attributes of the <IMG> element:

     ALIGN
          alignment of the image with respect to the text
          baseline. * `TOP' specifies that the top of the image
          aligns with the tallest item on the line contianing the
          image.

          * `MIDDLE' specifies that the center of the image
          aligns with the baseline of the line containing the
          image.

          * `BOTTOM' specifies that the bottom of the image
          aligns with the baseline of the line containing the
          image.

     ALT
                    Optional alternative text, for use in
                    non-graphical environments.

     ISMAP
                    indicates an image map (see 6.4, "Image Maps").

     SRC
                    specifies the URI of the image resource.

          NOTE - In practice, the media types of image resources
          are limited to a few raster graphic formats: typically
          `image/gif', `image/jpeg'. In particular, `text/html'
          resources are not intended to be used as image
          resources.

     Examples of use:

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

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

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


5. Character, Words, and Paragraphs

     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.


5.1. The ISO Latin 1 Character Repertoire

     The minimum character repertoire supported by all conforming
     HTML user agents is Latin Alphabet Nr. 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.

          NOTE - To support non-western writing systems, a larger
          character repertoire will be specified in a future
          version of HTML. The document character set will be
          ISO/IEC 10646-1, or some subset that agrees with
          ISO/IEC 10646-1; in particular, all numeric character
          references must use code positions assigned by ISO/IEC
          10646-1.

     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 8.4.2, "ISO Latin 1 Character Entity Set" for a table of
     the ``Added Latin 1'' entities, and 11.1, "The ANSI/ISO
     8859-1 Coded Character Set" for a table of the code
     positions of ANSI/ISO 8859-1.


6. Hyperlinks

     In addition to general purpose elements such as paragraphs
     and lists, HTML documents can express hyperlinks. A
     hyperlink is a relationship between two resources, called
     the source and the destination of the hyperlink. Each
     resource has a Uniform Resource Identifier (URI).

     An HTML user agent allows navigating a collection of these
     resources. In the following interactions, the URI of the
     source document is called the base URI.


6.1. Accessing Resources

     Each of the following markup constructs is the source of a
     hyperlink; these hyperlinks are references to resources to
     be processed in conjunction with the source documents:

          * <IMG> elements

          * <INPUT> elements with the SRC attribute present

          * <LINK> element

     To access the destination of a hyperlink, the base URI of
     the source document is combined with the value of the HREF
     or SRC attribute of the hyperlink element according to
     [RELURL]. The user agent disregards any fragment identifer,
     and uses the resulting URI to access the destination
     resource. For example, if a document identified as
     `http://host/x/y.html' contains:

     <img src="../icons/abc.gif">

     then the user agent must use the URI
     `http://host/icons/abc.gif' to access the resource linked
     from the <IMG> element.


6.2. Traversing Hyperlinks

     An <A> element with the HREF attribute present is an anchor;
     that is, the source of a hyperlink that is an option to
     navigate to another resource. The <LINK> element may also be
     an anchor.

     In addition to the base URI, the state of an HTML user agent
     includes a list of the anchors in the document. The user can
     traverse a hyperlink by choosing an anchor. The user agent
     then accesses the destination document as above and presents
     it.


6.2.1. Fragment Identifiers

     If the value of the <HREF> attribute of an anchor element
     contains a `#' character, then the characters after the `#'
     are a fragment identifier, not a part of the destination
     URI. As a degenerate case, `HREF="#fragment"' refers to an
     anchor in the same document: the source and destination URIs
     are the same.

     After accessing the destination resource, the navigation
     state (the scrollbar, for example) may be modified by a
     fragment identifer in the hyperlink source markup. The
     meaning of fragment identifiers depends on the media type of
     the destination resource. For `text/html' resources, it
     instructs the user agent to locate the <A> element with a
     NAME attribute whose value is the same as the fragment
     identifier. The matching is case sensitive.

     For example, if a user agent was processing the above
     document and the user indicated the following anchor:

     <p> See: <a href="app1.html#bannanas">appendix 1</a> for more detail
     on bannanas.</a>

     then the user agent URI must access the resource
     `http://host/x/app1.html'. Assuming the resource is
     represented using the `text/html' media type, the user agent
     must locate the anchor named `bannanas' and begin navigation
     there.

     The base URI for navigating the destination document may be
     different from the URI used to access it. For example, it
     may be replaced by by a <BASE> tag in the destination
     document or by an HTTP redirection transaction.


6.3. Queries and Indexes

     The <ISINDEX> element represents a set of hyperlinks. The
     user can choose from the set by providing keywords to the
     user agent. The user agent computes the destination URI by
     appending `?' and the keywords to the base URI. The keywords
     are escaped according to [URL] and joined by `+'. For
     example, if a document contains:

     <BASE HREF="http://host/index">
     <ISINDEX>

     and the user provides the keywords `apple' and `berry', then
     the user agent must access the resource
     `http://host/index?apple+berry'.

     <FORM> elements with `METHOD=GET' also represent sets of
     hyperlinks. See 7.2.2, "Query Forms: METHOD=GET" for
     details.


6.4. Image Maps

     The ISMAP attribute in combination with the <A> and <IMG>
     elements, represents a set of hyperlinks. The user can
     choose from the set by choosing a pixel of the image. The
     user agent computes the destination URI by appending `?' and
     the coordinates of the pixel to the URI given in the <A>
     element. For example, if a document contains:

     <head><title>ImageMap Example</title>
     <BASE HREF="http://host/index"></head>
     <body>
     <p> Choose any of these icons:<br>
     <a href="/cgi-bin/imagemap"><img ismap src="icons.gif"></a>

     and the user chooses the upper-leftmost pixel, then chosen
     hyperlink is the one with the URI
     `http://host/cgi-bin/image?0,0'.


7. Forms

     A form is a template for a form data set -- sequence of
     name/value pair fields -- with an associated method and
     action URI. The names are specified on the NAME attributes
     of form input elements, and the values are given by the
     user. The resulting form data set is used to access an
     information service as a function of the action and method.

     Forms elements can be mixed in with document structuring
     elements. For example, a <PRE> element may contain a <FORM>
     element, or a <FORM> element may contain lists which contain
     <INPUT> elements. This gives considerable flexibility in
     designing the layout of forms.

     Form processing is a level 2 feature.


7.1. Form Elements


7.1.1. Form: <FORM>

     The <FORM> element contains a sequence of input elements,
     along with document structuring elements. The attributes
     are:

     ACTION
                    specifies the action URI for the form. The ACTION
                    attribute defaults to the base URI of the document
                    (see 6, "Hyperlinks").

     METHOD
                    selects a method of accessing the action URI.

     ENCTYPE
                    specifies the media type used to encode the
                    name/value pairs for transport, in case the
                    protocol does not itself impose a format.


7.1.2. Input Field: <INPUT>

     The <INPUT> element represents a field for user input.
     Attributes are:

     ALIGN
                    vertical alignment of the image. For use only with
                    `TYPE=IMAGE'. The possible values are as for the
                    ALIGN attribute of the <IMG> element (see 4.10,
                    "Image: IMG").

     CHECKED
                    indicates that the initial state of a checkbox or
                    radio button is selected.

     MAXLENGTH
                    constrains the number of characters that can be
                    entered into a text input field. If the value of
                    MAXLENGTH is greater the the value of the SIZE
                    attribute, the field should scroll appropriately.
                    The default number of characters is unlimited.

     NAME
                    symbolic name for the form field corresponding to
                    this element or group of elements.

     SIZE
                    specifies the amount of display space allocated to
                    this input field according to its type.

     SRC
                    A URI specifying an image resource. For use only
                    with `TYPE=IMAGE'.

     TYPE
                    indicates type of the field. Defaults to `TEXT'.
                    Values are:

     CHECKBOX
                    an independent boolean value.

     HIDDEN
                    a hidden field. The user does not interact with
                    this field; instead, the VALUE attribute can be
                    used to specify a value.

     IMAGE
                    specifies an image resource to display, and allows
                    input of two form data: the x and y coordinate of
                    a pixel chosen from the image. The names of the
                    data are the name of this element with `.x' and
                    `.y' appended. `TYPE=IMAGE' implies `TYPE=SUBMIT'
                    processing; that is, when a pixel is chosen, the
                    form as a whole is submitted.

     PASSWORD
                    Similar to the TEXT attribute, except that the
                    value is obscured as it is entered.

     RADIO
                    a 1-of-many choice. All <INPUT> elements with
                    `TYPE=RADIO' and the same NAME combine into one
                    form field. The value of the form field is the
                    VALUE of the element chosen by the user. The
                    initial state may be indicated with the CHECKED
                    attribute. The VALUE attribute is required for
                    radio inputs.

     RESET
                    an input option, typically a button, that
                    instructs the user agent to reset the form's
                    fields to their initial states. Any VALUE
                    attribute indicates a label for the input
                    (button).

     SUBMIT
                    an input option, typically a button, that
                    instructs the user agent to submit the form. Any
                    VALUE attribute indicates a label for the input
                    (button). If the NAME attribute is present, this
                    element contributes a form field whose value is
                    given by the VALUE attribute. If the NAME
                    attribute is not present, this element does not
                    contribute a form field.

     TEXT
                    a single line text entry fields. The SIZE and
                    MAXLENGTH attributes may be used to constrain the
                    input or layout of the field. Use the <TEXTAREA>
                    element for mulit-line text fields.

     VALUE
                    The initial value of the field.


7.1.3. Selection: <SELECT>

     The <SELECT> element constrains the form field to an
     enumerated list of values. The values are given in <OPTION>
     elements. Attributes are:

     MULTIPLE
                    indicates that more than one option may be
                    included in the value.

     NAME
                    specifies the name of the form field.

     SIZE
                    specifies the number of visible items. Select
                    fields of size one are typically pop-down menus,
                    whereas select fields with size greater than one
                    are typically lists.

     For example:

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

     The initial state has the first option selected, unless a
     SELECTED attribute is present on any of the <OPTION>
     elements.


7.1.3.1. Option: <OPTION>

     The Option element can only occur within a Select element.
     It represents one choice, and has the following attributes:

     SELECTED
                    Indicates that this option is initially selected.

     VALUE
                    indicates the value to be returned if this option
                    is chosen. The field value defaults to the content
                    of the <OPTION> element.

     The content 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.


7.1.4. Text Area: <TEXTAREA>

     The <TEXTAREA> element represents a multi-line text field.
     For example:

     <TEXTAREA NAME="address" ROWS=64 COLS=6>
     HaL Computer Systems
     1315 Dell Avenue
     Campbell, California 95008
     </TEXTAREA>

     The content of the <TEXTAREA> element is the field's initial
     value.

     Typically, 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.


7.2. Form Submission

     An HTML user agent begins processing a form by presenting
     the document with the fields in their initial state. The
     user is allowed to modify the fields, constrained by the
     field type etc. When the user indicates that the form should
     be submitted (using a submit button or image input), the
     form data set is processed according to its method, action
     URI and enctype.

     When there is only one single-line text input field in a
     form, the user agent should accept Enter in that field as a
     request to submit the form.


7.2.1. The `application/x-www-form-urlencoded' Media Type

     The default encoding for all forms is
     `application/x-www-form-urlencoded'. A form data set is
     represented in this media type as follows:

          1. The form field names and values are escaped: space
          characterss are replaced by `+', and then reserved
          characters are escaped as per [URL]; that is,
          non-alphanumeric characters are replaced by `%HH', a
          percent sign and two hexadecimal digits representing
          the ASCII code of the character. Line breaks, as in
          multi-line textfield values, are represented as CR LF
          pairs, i.e. `%0D0A'.

          2. The fields are listed in the order they appear in
          the document with the name separated from the value by
          `=' and the pairs separated from each other by `&'.
          Fields with null values may be omitted. In particular,
          unselected radio buttons and checkboxes should not
          appear in the encoded data, but hidden fields with
          VALUE attributes present should.

          NOTE - The URI from a query form submission can be used
          in a normal anchor style hyperlink. Unfortunately, the
          use of the `&' character to separate form fields
          interacts with its use in SGML attribute values as an
          entity reference delimiter. For example, the URI
          `http://host/?x=1&y=2' must be written `<a
          href="http://host/?x=1&#38;y=2"' or `<a
          href="http://host/?x=1&#amp;y=2">'.
          HTTP server implementors, and in particular, CGI
          implementors are encouraged to support the use of `;'
          in place of `&' to save users the trouble of escaping
          `&' characters this way.


7.2.2. Query Forms: `METHOD=GET'

     If the processing of a form is idempotent (i.e. it has no
     lasting observable effect on the state of the world), then
     the form method should be `GET'. Many database searches have
     no visible side-effects and make ideal applications of query
     forms.

     To process a form whose action URL is an HTTP URL and whose
     method is `GET', the user agent starts with the action URI
     and appends a `?' and the form data set, in
     `application/x-www-form-urlencoded' format as above. The
     user agent then traverses the link to this URI just as if it
     were an anchor (see 6.2, "Traversing Hyperlinks").

          NOTE - The URL encoding may result in vary long URIs,
          which cause some historical HTTP server implementations
          to exhibit defective behavior. As a result, some HTML
          forms are written using `METHOD=POST' even though the
          form submission has no side-effects.


7.2.3. Forms with Side-Effects: `METHOD=POST'

     If the service associated with the processing of a form has
     side effects (for example, modification of a database or
     subscription to a service), the method should be `POST'.

     To process a form whose action URL is an HTTP URL and whose
     method is `POST', the user agent conducts an HTTP POST
     transaction using the action URI, and a message body of type
     `application/x-www-form-urlencoded' format as above. The
     user agent should display the response from the HTTP POST
     interaction just as it would display the response from an
     HTTP GET above.


7.2.4. Example Form Submission: Questionnaire Form

     Consider the following document:

     <title>Sample of HTML Form Submission</title>
     <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>

     The inital state of the form data set is:

     name
                    ``''

     gender
                    ``male''

     family
                    ``''

     other
                    ``''

     nickname
                    ``''

     Note that the radio input has an initial value, while the
     checkbox has none.

     The user might edit the fields and request that the form be
     submitted. At that point, suppose the values are:

     name
                    ``John Doe''

     gender
                    ``male''

     family
                    ``5''

     city
                    ``kent,miami''

     other
                    ``abc\ndef''

     nickname
                    ``J&D''

     The user agent then conducts an HTTP POST transaction using
     the URI `http://www.w3.org/sample'. The message body would
     be (ignore the linebreak):

     name=John+Doe&gender=male&family=5&city=kent%2Cmiami&
     other=abc%0D0Adef&nickname=J%26D


8. HTML Public Text


8.1. HTML DTD

     This is the Document Type Definition for the HyperText
     Markup Language.

<!--    html.dtd

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

        $Id: html.dtd,v 1.25 1995/03/29 18:53:13 connolly Exp $

        Author: Daniel W. Connolly <connolly@w3.org>
        See Also: html.decl, html-0.dtd, html-1.dtd
          http://info.cern.ch/hypertext/WWW/MarkUp/MarkUp.html
-->

<!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 "NAME"
        -- a list of these will be specified at a later date -->

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


8.2. 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
                ENTCAP          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
                    --
>
<!--
        $Id: html.decl,v 1.15 1995/05/06 01:44:47 connolly Exp $

        Author: Daniel W. Connolly <connolly@hal.com>

        See also: http://www.hal.com/%7Econnolly/html-spec
          http://info.cern.ch/hypertext/WWW/MarkUp/MarkUp.html
 -->


8.3. 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:

        -- catalog: SGML Open style entity catalog for HTML --
        -- $Id: catalog,v 1.2 1994/11/30 23:45:18 connolly Exp $ --

        -- 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


        -- Ways to refer to Strict Level 2: most general to most specific --
PUBLIC  "-//IETF//DTD HTML Strict//EN"                  html-s.dtd
PUBLIC  "-//IETF//DTD HTML 2.0 Strict//EN"              html-s.dtd
PUBLIC  "-//IETF//DTD HTML Strict Level 2//EN"          html-s.dtd
PUBLIC  "-//IETF//DTD HTML 2.0 Strict Level 2//EN"      html-s.dtd

        -- Ways to refer to Strict Level 1: most general to most specific --
PUBLIC  "-//IETF//DTD HTML Strict Level 1//EN"          html-1s.dtd
PUBLIC  "-//IETF//DTD HTML 2.0 Strict Level 1//EN"      html-1s.dtd

        -- Ways to refer to Strict Level 0: most general to most specific --
PUBLIC  "-//IETF//DTD HTML Strict Level 0//EN"          html-0s.dtd
PUBLIC  "-//IETF//DTD HTML 2.0 Strict Level 0//EN"      html-0s.dtd

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


8.4. Character Entity Sets

     The HTML DTD defines the following entities. They represent
     particular graphic characters which have special meanings in
     places in the markup, or may not be part of the character
     set available to the writer.


8.4.1. Numeric and Special Graphic Entity Set

     The following table lists each of the characters included
     from 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 include for the
     entire entity set -- only the entities listed below are
     included.

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


8.4.2. ISO Latin 1 Character Entity Set

     The following public text 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 includes the entire entity set.

<!-- (C) International Organization for Standardization 1986
     Permission to copy in any form is granted for use with
     conforming SGML systems and applications as defined in
     ISO 8879, provided this notice is included in all copies.
-->
<!-- Character entity set. Typical invocation:
     <!ENTITY % ISOlat1 PUBLIC
       "ISO 8879-1986//ENTITIES Added Latin 1//EN//HTML">
     %ISOlat1;
-->
<!--    Modified for use in HTML
        $Id: ISOlat1.sgml,v 1.2 1994/11/30 23:45:12 connolly Exp $ -->
<!ENTITY AElig  CDATA "&#198;" -- capital AE diphthong (ligature) -->
<!ENTITY Aacute CDATA "&#193;" -- capital A, acute accent -->
<!ENTITY Acirc  CDATA "&#194;" -- capital A, circumflex accent -->
<!ENTITY Agrave CDATA "&#192;" -- capital A, grave accent -->
<!ENTITY Aring  CDATA "&#197;" -- capital A, ring -->
<!ENTITY Atilde CDATA "&#195;" -- capital A, tilde -->
<!ENTITY Auml   CDATA "&#196;" -- capital A, dieresis or umlaut mark -->
<!ENTITY Ccedil CDATA "&#199;" -- capital C, cedilla -->
<!ENTITY ETH    CDATA "&#208;" -- capital Eth, Icelandic -->
<!ENTITY Eacute CDATA "&#201;" -- capital E, acute accent -->
<!ENTITY Ecirc  CDATA "&#202;" -- capital E, circumflex accent -->
<!ENTITY Egrave CDATA "&#200;" -- capital E, grave accent -->
<!ENTITY Euml   CDATA "&#203;" -- capital E, dieresis or umlaut mark -->
<!ENTITY Iacute CDATA "&#205;" -- capital I, acute accent -->
<!ENTITY Icirc  CDATA "&#206;" -- capital I, circumflex accent -->
<!ENTITY Igrave CDATA "&#204;" -- capital I, grave accent -->
<!ENTITY Iuml   CDATA "&#207;" -- capital I, dieresis or umlaut mark -->
<!ENTITY Ntilde CDATA "&#209;" -- capital N, tilde -->
<!ENTITY Oacute CDATA "&#211;" -- capital O, acute accent -->
<!ENTITY Ocirc  CDATA "&#212;" -- capital O, circumflex accent -->
<!ENTITY Ograve CDATA "&#210;" -- capital O, grave accent -->
<!ENTITY Oslash CDATA "&#216;" -- capital O, slash -->
<!ENTITY Otilde CDATA "&#213;" -- capital O, tilde -->
<!ENTITY Ouml   CDATA "&#214;" -- capital O, dieresis or umlaut mark -->
<!ENTITY THORN  CDATA "&#222;" -- capital THORN, Icelandic -->
<!ENTITY Uacute CDATA "&#218;" -- capital U, acute accent -->
<!ENTITY Ucirc  CDATA "&#219;" -- capital U, circumflex accent -->
<!ENTITY Ugrave CDATA "&#217;" -- capital U, grave accent -->
<!ENTITY Uuml   CDATA "&#220;" -- capital U, dieresis or umlaut mark -->
<!ENTITY Yacute CDATA "&#221;" -- capital Y, acute accent -->
<!ENTITY aacute CDATA "&#225;" -- small a, acute accent -->
<!ENTITY acirc  CDATA "&#226;" -- small a, circumflex accent -->
<!ENTITY aelig  CDATA "&#230;" -- small ae diphthong (ligature) -->
<!ENTITY agrave CDATA "&#224;" -- small a, grave accent -->
<!ENTITY aring  CDATA "&#229;" -- small a, ring -->
<!ENTITY atilde CDATA "&#227;" -- small a, tilde -->
<!ENTITY auml   CDATA "&#228;" -- small a, dieresis or umlaut mark -->
<!ENTITY ccedil CDATA "&#231;" -- small c, cedilla -->
<!ENTITY eacute CDATA "&#233;" -- small e, acute accent -->
<!ENTITY ecirc  CDATA "&#234;" -- small e, circumflex accent -->
<!ENTITY egrave CDATA "&#232;" -- small e, grave accent -->
<!ENTITY eth    CDATA "&#240;" -- small eth, Icelandic -->
<!ENTITY euml   CDATA "&#235;" -- small e, dieresis or umlaut mark -->
<!ENTITY iacute CDATA "&#237;" -- small i, acute accent -->
<!ENTITY icirc  CDATA "&#238;" -- small i, circumflex accent -->
<!ENTITY igrave CDATA "&#236;" -- small i, grave accent -->
<!ENTITY iuml   CDATA "&#239;" -- small i, dieresis or umlaut mark -->
<!ENTITY ntilde CDATA "&#241;" -- small n, tilde -->
<!ENTITY oacute CDATA "&#243;" -- small o, acute accent -->
<!ENTITY ocirc  CDATA "&#244;" -- small o, circumflex accent -->
<!ENTITY ograve CDATA "&#242;" -- small o, grave accent -->
<!ENTITY oslash CDATA "&#248;" -- small o, slash -->
<!ENTITY otilde CDATA "&#245;" -- small o, tilde -->
<!ENTITY ouml   CDATA "&#246;" -- small o, dieresis or umlaut mark -->
<!ENTITY szlig  CDATA "&#223;" -- small sharp s, German (sz ligature) -->
<!ENTITY thorn  CDATA "&#254;" -- small thorn, Icelandic -->
<!ENTITY uacute CDATA "&#250;" -- small u, acute accent -->
<!ENTITY ucirc  CDATA "&#251;" -- small u, circumflex accent -->
<!ENTITY ugrave CDATA "&#249;" -- small u, grave accent -->
<!ENTITY uuml   CDATA "&#252;" -- small u, dieresis or umlaut mark -->
<!ENTITY yacute CDATA "&#253;" -- small y, acute accent -->
<!ENTITY yuml   CDATA "&#255;" -- small y, dieresis or umlaut mark -->


9. Glossary

     absolute URI
                    a URI in absolute form, as per [URL]

     anchor
                    a hyperlink navigation option; typically, a
                    highlighted phrase marked as an <A> element.

     base URI
                    URI used as the base of an HTML document for the
                    purpose of resolving hyperlink destinations.

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

     character
     encoding scheme
                    A function whose domain is the set of sequences of
                    octets, and whose range is the set of sequences of
                    characters from a character repertoire; that is, a
                    sequence of octets and a character encoding scheme
                    determines a sequence of characters.

     character
     repertoire
                    A finite set of characters; e.g. the range of a
                    coded character set.

     code position
                    An integer. A coded character set and a code
                    position from its domain determine a character.

     coded character
     set
                    A function whose domain is a subset of the
                    integers and whose range is a character
                    repertoire. That is, for some set of integers
                    (usually of the form {0, 1, 2, ..., N} ), a coded
                    character set and an integer in that set determine
                    a character. Conversely, a character and a coded
                    character set determine the character's code
                    position (or, in rare cases, a few code
                    positions).

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

     data character
                    Characters other than markup, which make up the
                    content of elements.

     document
     character set
                    a coded character set whose range includes all
                    characters used in a document. Every SGML document
                    has exactly one document character set. Numeric
                    character references are resolved via the document
                    character set.

     DTD
                    document type definition. Rules that apply SGML to
                    the markup of documents of a particular type,
                    including a set of element and entity
                    declarations. [SGML]

     element
                    A component of the hierarchical structure defined
                    by a document type definition; it is identified in
                    a document instance by descriptive markup, sually
                    a start-tag and end-tag. [SGML]

     end-tag
                    Descriptive markup that identifies the end of an
                    element. [SGML]

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

     fragment
     identifier
                    the portion of an HREF attribute value following
                    the `#' character which modifies the prenentation
                    of the destination of a hyperlink.

     form data set
                    a sequence of name/value pairs; the names are
                    given by an HTML document and the values are given
                    by a user.

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

     hyperlink
                    a relationship between to resources, called the
                    source and the destination.

     markup
                    Syntactically delimited characters added to the
                    data of a document to represent its structure.
                    There are four different kinds of markup:
                    descriptive markup (tags), references, markup
                    declarations, and processing instructions.[SGML]

     may
                    A document or user interface is conforming whether
                    this statement applies or not.

     media type
                    an Internet Media Type, as per [IMEDIA].

     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. [MIME]

     minimally
     conforming HTML
     user agent
                    A user agent that conforms to this specification
                    except for form processing. It may only process
                    level 1 HTML documents.

     must
                    Documents or user agents in conflict with this
                    statement are not conforming.

     SGML document
                    A sequence of characters organized physically as a
                    set of entities and logically into a hierarchy of
                    elements. An SGML document consists of data
                    characters and markup; the markup describes the
                    structure of the information and an instance of
                    that structure.[SGML]

     shall
                    If a document or user agent conflicts with this
                    statement, it does not conform to this
                    specification.

     should
                    If a document or user agent conflicts with this
                    statement, undesirable results may occur in
                    practice even though it conforms to this
                    specification.

     start-tag
                    Descriptive markup that identifies the start of an
                    element and specifies its generic identifier and
                    attributes. [SGML]


     syntax-reference
     character set
                    A coded character set whose range includes all
                    characters used for markup; e.g. name characters
                    and delimiter characters.

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

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

     typical
                    Typical processing 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.

     URI
                    A Universal Resource Identifier is a formatted
                    string that serves as an identifier for a
                    resource, typcally on the Internet. URIs are used
                    in HTML to identify the destination of hyperlinks.
                    URIs in common practice include Uniform Resource
                    Locators (URLs)[URL] and Relative URLs[RELURL].

     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.

     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.
                    `http://www.w3.org/'


10. Bibliography

     [URI]
                    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.

     [URL]
                    T. Berners-Lee, L. Masinter, and M. McCahill.
                    ``Uniform Resource Locators (URL).'' RFC 1738,
                    CERN, Xerox PARC, University of Minnesota, October
                    1994.

     [HTTP]
                    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.

     [MIME]
                    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.

     [RELURL]
                    R. T. Fielding. ``Relative Uniform Resource
                    Locators.'' Work in Progress
                    (draft-ietf-uri-relative-url-06.txt), UC Irvine,
                    March 1995.

     [GOLD90]
                    C. F. Goldfarb. ``The SGML Handbook.'' Y.
                    Rubinsky, Ed., Oxford University Press, 1990.

     [IMEDIA]
                    J. Postel. ``Media Type Registration Procedure.''
                    RFC 1590, USC/ISI, March 1994.

     [IANA]
                    J. Reynolds and J. Postel. ``Assigned Numbers.''
                    STD 2, RFC 1700, USC/ISI, October 1994.

     [SQ91]
                    SoftQuad. ``The SGML Primer.'' 3rd ed., SoftQuad
                    Inc., 1991.

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

     [ISO-8859-1]
                    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.

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


11. Appendices

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


11.1. The ANSI/ISO 8859-1 Coded Character Set

     This list, sorted numerically, is derived from ANSI/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


11.2. Obsolete Features

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


11.2.1. 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 interpreters (see Section 2.2.5).


11.2.2. 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.


11.2.3. 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


11.2.4. 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:

          * The text may contain any ISO Latin-1 printable
          characters, except 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.

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

          * 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.

          * 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.


11.3. Proposed Features

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


11.3.1. 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;


11.3.2. 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.


11.3.3. 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.


11.3.4. 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 interpreters.

     Example of use:

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


12. 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


12.1. 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
     URI: http://www.w3.org/hypertext/WWW/People/Connolly/