HTML Working Group                                         T. Berners-Lee
INTERNET-DRAFT                                                    MIT/W3C
<draft-ietf-html-spec-02.txt>                                 D. Connolly
Expires: In six months                                        May 6, 1995

                   Hypertext Markup Language - 2.0


     1.  Introduction
     2.  HTML as an Application of SGML
     3.  HTML as an Internet Media Type
     4.  Document Structure Elements
     5.  Character Content
     6.  Data Elements
     7.  Character Format Elements
     8.  Hyperlink Elements
     9.  Block Structuring Elements
     10.  Form-based Input Elements
     11.  HTML Public Text
     12.  Glossary
     13.  Bibliography
     14.  Appendices
     15.  Acknowledgments

Status of this Memo

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     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

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 11.1, "HTML DTD")
          * 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
          * Its document character set includes ISO-8859-1 and
          agrees with ISO10646; that is, each code position
          listed in 14.1, "The 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 crititcal distinction is that
          numeric character references agree with ISO10646
          regardless of how the document is encoded.

          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

          HTML documents should not contain these idioms, at
          least until such time as support for them is widely

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

                    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.

                    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

                    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 as per [SGML].
          * It supports the ISO-8859-1 character encoding scheme,
          and processes each character in the ISO Latin Alphabet
          Nr. 1 as specified in 5.1, "The ISO Latin 1 Character
          NOTE - To support non-western writing systems, HTML
          user agents should support the Unicode-1-1-UTF-8 and
          Unicode-1-1-UCS-2 encodings and as much of the
          character repertoire of ISO10646 as is possible as
          * 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.

          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.

2. HTML as an Application of SGML

     HTML is an application of ISO Standard 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 11, "HTML Public

     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 is given
     in 11.2, "SGML Declaration for HTML". According to the
     document character set there,`&#42;' refers to an asterisk

     The instance above is regarded as the following sequence of

          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

     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' (11.1, "HTML DTD"). Hence the
     terminals above parse as:

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

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 ISO-646-IRV character repertoire. Data
     characters are drawn from the document character set (see 5,
     "Character Content").

     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

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

     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
              &       &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
          techinques 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, 11.1, "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.
          * A name token (a sequence of letters, digits, periods,
          or hyphens)

     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">

          NOTE - Some historical implementations consider any
          occurrence of the `>' character to signal the end of a
          tag. For ompatibility with such implementations, when
          `>' appears in an attribute value, it should be
          represented with a numeric character reference, such as
          in: `<IMG SRC="eq1.jpg" alt="a>b">'.

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

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

     For example:

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

          NOTE - Some historical implementations allow any
          character except space or `>' in a name token.
          Attributes values must be quoted only if they don't
          satisfy the syntax for a name token.

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

     Attributes such as ISMAP and COMPACT, may be written using a
     minimized syntax. The markup:

     <UL COMPACT="compact">

     can be written using a minimized syntax:


          NOTE - Some historical implementations only understand
          the minimized syntax.


     To include comments in an HTML document that will be
     eliminated in the mapping to terminals, surround them with
     `<!--' and `-->'. After the comment delimiter, all text up
     to the next occurrence of `-->' is ignored. Hence comments
     cannot be nested. White space is allowed between the closing
     `--' and `>', but not between the opening `<!' and `--'.

     For example:

     <TITLE>HTML Guide: Recommended Usage</TITLE>
     <!-- $Id: html-sgml.sgm,v 1.4 1995/05/06 01:44:46 connolly Exp $ -->

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

2.2.6. Example HTML Document

     <!-- Here's a good place to put a comment. -->
     <TITLE>Structural Example</TITLE>
     <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>
     <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.
     <LI>Third item in an ordered list.
     <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.
     <IMG SRC ="triangle.xbm" alt="Warning: ">
     Be sure to read these <b>bold instructions</b>.

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 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

     Media subtype


                    version, charset

                    any encoding is allowed

                    see 3.3, "Security Considerations"

     The optional parameters are defined as follows:

                    To help avoid future compatibility problems, the
                    version parameter may be used to give the version
                    number of the specification to which the document
                    conforms. The version number appears at the front
                    of this document and within the public identifier
                    of the HTML DTD. This specification defines
                    version 2.0. There is no default.

                    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

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

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

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

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

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 -- should be aware and make their users
     aware of the lack of confidentiality.


4. Document Structure Elements

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


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

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

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

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

4.1. HTML Document Element

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

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

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


4.2. Head

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

     The head of an HTML document is an unordered collection of
     information about the document. The Title element is

     <TITLE>Introduction to HTML</TITLE>

4.3. Body

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

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

4.4. Title

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

     Every HTML document must contain a Title element. The title
     should identify the contents of the document in a global
     context, and may be used in history lists and as a label for
     the window displaying the document. Unlike headings, titles
     are not rendered in the text of a document itself.

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

          NOTE - The length of a title is not limited; however,
          long titles may be truncated in some applications. To
          minimize this possibility, titles should be fewer than
          64 characters. Also keep in mind that a short title,
          such as Introduction, may be meaningless out of
          context. An example of a meaningful title might be
          ``Introduction to HTML Elements.''

4.5. Base

     <BASE> Level 0

     The Base element allows the URI of the document itself to be
     recorded in situations in which the document may be read out
     of context. URIs within the document may be in a ``partial''
     form relative to this base address[RELURL].

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

4.6. Isindex

     <ISINDEX> Level 0

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

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

4.7. Link

     <LINK> Level 0

     The Link element indicates a relationship between the
     document and some other object. A document may have any
     number of Link elements.

     The Link element is empty (does not have a closing tag), but
     takes the same attributes as the Anchor element.

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

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

4.8. Meta

     <META> Level 0

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

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

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

     Attributes of the META element:

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

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

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


     If the document contains:

     <META HTTP-EQUIV="Expires"
     &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;CONTENT="Tue, 04 Dec 1993 21:29:02 GMT">
     <meta http-equiv="Keywords" CONTENT="Fred, Barney">
     <META HTTP-EQUIV="Reply-to"
     &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;content=" (Roy Fielding)">

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

     Expires: Tue, 04 Dec 1993 21:29:02 GMT
     Keywords: Fred, Barney
     Reply-to: (Roy Fielding)

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

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

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

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

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

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

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

4.9. Nextid

     <NEXTID> Level 0

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

     <NEXTID N=Z27>

     When modifying a document, existing anchor identifiers
     should not be reused, as these identifiers may be referenced
     by other documents. Human writers of HTML usually use
     mnemonic alphabetical identifiers.

     HTML interpreters may ignore the Nextid element. Support for
     the Nextid element does not impact HTML interpreters in any

5. Character Content

     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.

     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

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

     See 11.4.2, "ISO Latin 1 Character Entity Set" for a table
     of the ``Added Latin 1'' entities, and 14.1, "The ISO-8859-1
     Coded Character Set" for a table of the code positions of

6. Data Elements

6.1. Line Break

     <BR> Level 0

     The Line Break element specifies that a new line must be
     started at the given point. A new line indents the same as
     that of line-wrapped text.

     Example of use:

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

6.2. Horizontal Rule

     <HR> Level 0

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

     Example of use:

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

6.3. Image

     <IMG> Level 0

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

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

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

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

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

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

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

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

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

     Example of use:

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

7. Character Format Elements

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

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

     Character format tags may be ignored by minimal HTML

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

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

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

7.1. Semantic Format Elements

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

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

7.1.1. Citation

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

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

7.1.2. Code

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

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

7.1.3. Emphasis

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

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

7.1.4. Keyboard

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

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

7.1.5. Sample

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

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

7.1.6. Strong

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

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

7.1.7. Variable

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

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

7.2. Physical Format Elements

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

7.2.1. Bold

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

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

7.2.2. Italic

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

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

7.2.3. Teletype

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

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

8. Hyperlink Elements

8.1. Anchor

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

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

     Attributes of the `<A>' tag:

8.1.1. HREF

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


     See <A HREF="">HaL</A>'s
     information for more details.

     In this example, selecting ``HaL'' takes the reader to a
     document at The format of the network
     address is specified in the URI specification for print

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


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

     In this example, selecting ``glossary'' takes the reader to
     another anchor (i.e., <A NAME=``glossary''>Glossary</A>) in
     the same document. The NAME attribute is described below. If
     the anchor is in another document, the HREF attribute may be
     relative to the document's address or the specified base
     address (see 4.5, "Base").

8.1.2. NAME

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

     Example of use:

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

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

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

8.1.3. TITLE

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

8.1.4. REL

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

8.1.5. REV

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

8.1.6. URN

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

8.1.7. METHODS

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

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

9. Block Structuring Elements

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

9.1. Paragraph

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

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

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

     Example of use:

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

9.2. Preformatted Text

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

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

     The <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 interpreter to
     select a suitable font and indentation. If the WIDTH
     attribute is not present, a width of 80 characters is
     assumed. Where the WIDTH attribute is supported, widths of
     40, 80 and 132 characters should be presented optimally,
     with other widths being rounded up.

     Within preformatted text:

          * Line breaks within the text are rendered as a move to
          the beginning of the next line.
          * Anchor elements and character highlighting elements
          may be used.
          * Elements that define paragraph formatting (headings,
          address, etc.) must not be used.
          * The horizontal tab character (encoded in US-ASCII and
          ISO-8859-1 as decimal 9) must be interpreted as the
          smallest positive nonzero number of spaces which will
          leave the number of characters so far on the line as a
          multiple of 8. Its use is not recommended however.

          NOTE - 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.

          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

     Example of use:

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

          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 interpreter to faithfully render
          character formatting elements.

9.3. Address

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

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

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

     Example of use:

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

9.4. Blockquote

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

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

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

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

     Example of use:

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

9.5. Headings

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

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

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

     Example of use:

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

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

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

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

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

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

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

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

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

9.6. List Elements

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

9.6.1. Definition List

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

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

     Example of use:

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

     If the DT term does not fit in the DT column (one third of
     the display area), it may be extended across the page with
     the DD section moved to the next line, or it may be wrapped
     onto successive lines of the left hand column.

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

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

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

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

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

     <DT>Term<DD>This is the first definition in compact format.
     <DT>Term<DD>This is the second definition in compact format.

9.6.2. Directory List

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

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

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


9.6.3. Menu List

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

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

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

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

9.6.4. Ordered List

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

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

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

     <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.
     <LI>Click highlighted text to move from one link to another.

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

9.6.5. Unordered List

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

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

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

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

10. Form-based Input Elements

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

     The following elements are used to create forms:

                    A form within a document.

                    One input field.

                    One option within a Select element.

                    A selection from a finite set of options.

                    A multi-line input field.

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

     Example of use (a questionnaire form):

     <H1>Sample Questionnaire</H1>
     <P>Please fill out this questionnaire:
     <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:
     <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>
     Nickname: <INPUT NAME="nickname" SIZE="42">
     <P>Thank you for responding to this questionnaire.

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

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

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

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

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

10.1. Form

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

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

     The ACTION attribute is a URI specifying the location to
     which the contents of the form is submitted to elicit a
     response. If the ACTION attribute is missing, the URI of the
     document itself is assumed. The way data is submitted varies
     with the access protocol of the URI, and with the values of
     the METHOD and ENCTYPE attributes.

     In general:

          * the METHOD attribute selects variations in the
          * the ENCTYPE attribute specifies the format of the
          submitted data in case the protocol does not impose a
          format itself.

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

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

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

10.2. Input

     <INPUT> Level 2

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

     Attributes of the Input element:

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

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

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

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

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

     INPUT TYPE=text SIZE="24"

                    A URI specifying an image. For use only with

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

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

                    No field is presented to the user, but the content
                    of the field is sent with the submitted form. This
                    value may be used to transmit state information
                    about client/server interaction.

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

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

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

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

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

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

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

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

10.3. Option

     <OPTION> Level 2

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

                    Indicates that this option is initially selected.

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

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

10.4. Select

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

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

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

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

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

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

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

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

10.5. Text Area

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

     The Textarea element lets users enter more than one line of
     text. For example:

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

     The text up to the end tag (</TEXTAREA>) is used to
     initialize the field's value. This end tag is always
     required even if the field is initially blank. When
     submitting a form, lines in a TEXTAREA should be terminated
     using CRLF.

     In a typical rendering, the ROWS and COLS attributes
     determine the visible dimension of the field in characters.
     The field is rendered in a fixed-width font. HTML
     interpreters should allow text to extend beyond these limits
     by scrolling as needed.

          NOTE - In the initial design for forms, multi-line text
          fields were supported by the Input element with
          TYPE=TEXT. Unfortunately, this causes problems for
          fields with long text values. SGML's default (Reference
          Quantity Set) limits the length of attribute literals
          to only 240 characters. The HTML 2.0 SGML declaration
          increases the limit to 1024 characters.

11. HTML Public Text

11.1. 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 <>
             See Also: html.decl, html-0.dtd, html-1.dtd

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

                 <!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML//EN">
 20              ...

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

     <!ENTITY % HTML.Recommended "IGNORE"
             -- Certain features of the language are necessary for
 30             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.
 35          -->

     <![ %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,
 45             and their use is deprecated. This feature test entity
                enables a document type definition that eliminates
                these features.

 50  <!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
 60          -->

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

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

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

             -- The term URI means a CDATA attribute
 75             whose value is a Uniform Resource Identifier,
                as defined by
             "Universal Resource Identifiers" by Tim Berners-Lee
             aka RFC 1630

 80          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">

100  <!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
110  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
115  SDA & ICADD:
             - ISO 12083:1993, Annex A.8, Facilities for Braille,
               large print and computer voice
             - ICADD ListServ
120          - Usenet news group bit.listserv.easi
             - Recording for the Blind, +1 800 221 4792

125            -- one to one mapping        -->
               -- context-sensitive mapping -->
               -- generated text prefix     -->
               -- generated text suffix     -->
               -- suspend transform process -->

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

     <![ %HTML.Highlighting [

140  <!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"
150  <!ATTLIST ( B | STRONG )
             %SDAFORM; "B"
     <!ATTLIST ( I | EM | CITE )
             %SDAFORM; "It"
155          >

     <!-- <TT>       Typewriter text                         -->
     <!-- <B>        Bold text                               -->
     <!-- <I>        Italic text                             -->
     <!-- <EM>       Emphasized phrase                       -->
     <!-- <STRONG>   Strong emphais                          -->
     <!-- <CODE>     Source code phrase                      -->
     <!-- <SAMP>     Sample text or characters               -->
165  <!-- <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">

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

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

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

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

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

     <!ENTITY % linkExtraAttributes
195          "REL %linkType #IMPLIED
             REV %linkType #IMPLIED
             URN CDATA #IMPLIED
200          ">

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

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

     <!ELEMENT A     - - %A.content -(A)>
     <!ATTLIST A
             HREF %URI #IMPLIED
215          NAME %linkName #IMPLIED
             %SDAPREF; "<Anchor: #AttList>"
     <!-- <A>                Anchor; source/destination of link      -->
220  <!-- <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     -->
225  <!-- <A TITLE="...">    Title of destination (advisory)         -->
     <!-- <A METHODS="...">  Operations on destination (advisory)    -->

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

240  <!-- <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
250          %SDAFORM; "Para"

     <!-- <P>        Paragraph       -->

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

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

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

265  <!ELEMENT ( %heading )  - -  (%text;)*>
     <!ATTLIST H1
             %SDAFORM; "H1"
     <!ATTLIST H2
270          %SDAFORM; "H2"
     <!ATTLIST H3
             %SDAFORM; "H3"
275  <!ATTLIST H4
             %SDAFORM; "H4"
     <!ATTLIST H5
             %SDAFORM; "H5"
280          >
     <!ATTLIST H6
             %SDAFORM; "H6"

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

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

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

     <!ENTITY % block.forms "BLOCKQUOTE">
     <![ %HTML.Deprecated [
             <!ENTITY % preformatted "PRE | XMP | LISTING">

305  <!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)*>
             WIDTH NUMBER #implied
             %SDAFORM; "Lit"

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

     <![ %HTML.Deprecated [

325  <!ENTITY % literal "CDATA"
             -- historical, non-conforming parsing mode where
                the only markup signal is the end tag
                in full
     <!ELEMENT (XMP|LISTING) - -  %literal>
             %SDAFORM; "Lit"
             %SDAPREF; "Example:&#RE;"
335          >
             %SDAFORM; "Lit"
             %SDAPREF; "Listing:&#RE;"
     <!-- <XMP>              Example section         -->
     <!-- <LISTING>          Computer listing        -->

     <!ELEMENT PLAINTEXT - O %literal>
345  <!-- <PLAINTEXT>        Plain text passage      -->

             %SDAFORM; "Lit"
350  ]]>

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

355  <!ELEMENT DL    - -  (DT | DD)+>
             %SDAFORM; "List"
             %SDAPREF; "Definition List:"
360          >

     <!ELEMENT DT    - O (%text)*>
             %SDAFORM; "Term"
365          >

     <!ELEMENT DD    - O %flow>
             %SDAFORM; "LItem"
370          >

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

     <!ELEMENT (OL|UL) - -  (LI)+>
380          %SDAFORM; "List"
             %SDAFORM; "List"
385          >
     <!-- <UL>               Unordered list                  -->
     <!-- <UL COMPACT>       Compact list style              -->
     <!-- <OL>               Ordered, or numbered list       -->
     <!-- <OL COMPACT>       Compact list style              -->

     <!ELEMENT (DIR|MENU) - -  (LI)+ -(%block)>
395          %SDAFORM; "List"
             %SDAPREF; "<LHead>Directory</LHead>"
400          %SDAFORM; "List"
             %SDAPREF; "<LHead>Menu</LHead>"

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

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

     <!-- <LI>               List item                       -->
     <!--========== Document Body ===================-->

     <![ %HTML.Recommended [
             <!ENTITY % body.content "(%heading|%block|HR|ADDRESS|IMG)*"
420          -- <h1>Heading</h1>
                <p>Text ...
                     is preferred to
                Text ...
425          -->

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

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

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

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

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

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

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

     <![ %HTML.Forms [

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

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

     <!ENTITY % InputType "(TEXT | PASSWORD | CHECKBOX |
470                          RADIO | SUBMIT | RESET |
                             IMAGE | HIDDEN )">
             TYPE %InputType TEXT
475          NAME CDATA #IMPLIED
             SRC %URI #IMPLIED
             SIZE CDATA #IMPLIED
             ALIGN (top|middle|bottom) #IMPLIED
             %SDAPREF; "Input: "

485  <!-- <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                -->
490  <!-- <INPUT CHECKED>            Initial state is "on"           -->
     <!-- <INPUT SIZE=...>           Field size hint                 -->
     <!-- <INPUT MAXLENGTH=...>      Data length maximum             -->
     <!-- <INPUT ALIGN=...>          Image alignment                 -->

500          %SDAFORM; "List"
             "<LHead>Select #AttVal(Multiple)</LHead>"

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

             %SDAFORM; "LItem"
515          %SDAPREF;
             "Option: #AttVal(Value) #AttVal(Selected)"

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

             %SDAFORM; "Para"
             %SDAPREF; "Input Text -- #AttVal(Name): "
530          >

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


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

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

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

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

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

     <!-- <TITLE>    Title of document -->
             HREF %URI #REQUIRED
565          %SDAPREF; "Linked to : #AttVal (TITLE) (URN) (HREF)>"    >

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

        "<Para>[Document is indexed/searchable.]</Para>">

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

             HREF %URI; #REQUIRED     >
     <!-- <BASE>             Base context document                   -->
     <!-- <BASE HREF="...">  Address for this document               -->

             N %linkName #REQUIRED     >

     <!-- <NEXTID>           Next ID to use for link name            -->
     <!-- <NEXTID N=...>     Next ID to use for link name            -->
             HTTP-EQUIV  NAME    #IMPLIED
             NAME        NAME    #IMPLIED
600          CONTENT     CDATA   #REQUIRED    >

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

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

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

     <!ELEMENT HTML O O  (%html.content)>
615  <!ENTITY % version.attr "VERSION CDATA #FIXED '%HTML.Version;'">

             %SDAFORM; "Book"
620          >

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

11.2. 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).

  5  --

              BASESET  "ISO 646:1983//CHARSET
                        International Reference Version
 10                     (IRV)//ESC 2/5 4/0"
              DESCSET  0   9   UNUSED
                       9   2   9
                       11  2   UNUSED
                       13  1   13
 15                    14  18  UNUSED
                       32  95  32
                       127 1   UNUSED
          BASESET   "ISO Registration Number 100//CHARSET
                     ECMA-94 Right Part of
 20                  Latin Alphabet Nr. 1//ESC 2/13 4/1"

              DESCSET  128  32   UNUSED
                       160  96    32

                     TOTALCAP        150000
                     GRPCAP          150000
                     ENTCAP          150000

              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
 35                     International Reference Version
                        (IRV)//ESC 2/5 4/0"
              DESCSET  0 128 0
                       RE          13
 40                    RS          10
                       SPACE       32
                       TAB SEPCHAR  9

 45           NAMING   LCNMSTRT ""
                       UCNMSTRT ""
                       LCNMCHAR ".-"
                       UCNMCHAR ".-"
                       NAMECASE GENERAL YES
 50                             ENTITY  NO
              DELIM    GENERAL  SGMLREF
                       SHORTREF SGMLREF
              NAMES    SGMLREF
              QUANTITY SGMLREF
 55                    ATTSPLEN 2100
                       LITLEN   1024
                       NAMELEN  72    -- somewhat arbitrary; taken from
                                     internet line length conventions --
                       PILEN    1024
 60                    TAGLEN   2100
                       GRPGTCNT 150
                       GRPCNT   64

         DATATAG  NO
         OMITTAG  YES
         RANK     NO
 70    LINK
         SIMPLE   NO
         IMPLICIT NO
         EXPLICIT NO
 75      CONCUR   NO
         SUBDOC   NO
         FORMAL   YES
       APPINFO    "SDA"  -- conforming SGML Document Access application
 80  >
             $Id: html.decl,v 1.15 1995/05/06 01:44:47 connolly Exp $

             Author: Daniel W. Connolly <>
             See also:

11.3. 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 --
  5  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

 10          -- 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 --
 15  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 \
  &  --
 20  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

 25          -- 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 \
  &  --
 30  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"\
  &  ml

11.4. 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.

11.4.1. 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

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

11.4.2. 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.
  5  -->
     <!-- Character entity set. Typical invocation:
          <!ENTITY % ISOlat1 PUBLIC
            "ISO 8879-1986//ENTITIES Added Latin 1//EN//HTML">
 10  -->
     <!--    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 -->
 15  <!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 -->
 20  <!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 -->
 25  <!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 -->
 30  <!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 -->
 35  <!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 -->
 40  <!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 -->
 45  <!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 -->
 50  <!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 -->
 55  <!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 -->
 60  <!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 -->
 65  <!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 -->
 70  <!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 -->

12. Glossary

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

     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.

                    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
                    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

     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.

     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.

                    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]

                    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]

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

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

     HTML document
                    An SGML document conforming to this document type

                    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]

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

     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]

                    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]

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

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

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

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

                    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

                    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

                    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 hypertext
                    links, the source of in-line images, and the
                    object of form actions. URIs in common use include
                    Uniform Resource Locators (URLs)[URL] and Relative

     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

                    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.

13. Bibliography

                    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.

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

                    T. Berners-Lee, R. T. Fielding, and H. Frystyk
                    Nielsen. ``Hypertext Transfer Protocol -
                    HTTP/1.0.'' Work in Progress
                    (, MIT, UC Irvine,
                    CERN, March 1995.

                    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.

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

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

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

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

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

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

                    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.

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

14. Appendices

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

14.1. The ISO-8859-1 Coded Character Set

     This list, sorted numerically, is derived from ISO-8859-1
     8-bit single-byte coded graphic character set:

     &#00; - &#08;   Unused
     &#09;           Horizontal tab
     &#10;           Line feed
     &#11; - &#31;   Unused
     &#32;           Space
     &#33;           Exclamation mark
     &#34;           Quotation mark
     &#35;           Number sign
     &#36;           Dollar sign
     &#37;           Percent sign
     &#38;           Ampersand
     &#39;           Apostrophe
     &#40;           Left parenthesis
     &#41;           Right parenthesis
     &#42;           Asterisk
     &#43;           Plus sign
     &#44;           Comma
     &#45;           Hyphen
     &#46;           Period (fullstop)
     &#47;           Solidus (slash)
     &#48; - &#57;   Digits 0-9
     &#58;           Colon
     &#59;           Semi-colon
     &#60;           Less than
     &#61;           Equals sign
     &#62;           Greater than
     &#63;           Question mark
     &#64;           Commercial at
     &#65; - &#90;   Letters A-Z
     &#91;           Left square bracket
     &#92;           Reverse solidus (backslash)
     &#93;           Right square bracket
     &#94;           Caret
     &#95;           Horizontal bar (underscore)
     &#96;           Acute accent
     &#97; - &#122;  Letters a-z
     &#123;          Left curly brace
     &#124;          Vertical bar
     &#125;          Right curly brace
     &#126;          Tilde
     &#127; - &#160; Unused
     &#161;          Inverted exclamation
     &#162;          Cent sign
     &#163;          Pound sterling
     &#164;          General currency sign
     &#165;          Yen sign
     &#166;          Broken vertical bar
     &#167;          Section sign
     &#168;          Umlaut (dieresis)
     &#169;          Copyright
     &#170;          Feminine ordinal
     &#171;          Left angle quote, guillemotleft
     &#172;          Not sign
     &#173;          Soft hyphen
     &#174;          Registered trademark
     &#175;          Macron accent
     &#176;          Degree sign
     &#177;          Plus or minus
     &#178;          Superscript two
     &#179;          Superscript three
     &#180;          Acute accent
     &#181;          Micro sign
     &#182;          Paragraph sign
     &#183;          Middle dot
     &#184;          Cedilla
     &#185;          Superscript one
     &#186;          Masculine ordinal
     &#187;          Right angle quote, guillemotright
     &#188;          Fraction one-fourth
     &#189;          Fraction one-half
     &#190;          Fraction three-fourths
     &#191;          Inverted question mark
     &#192;          Capital A, grave accent
     &#193;          Capital A, acute accent
     &#194;          Capital A, circumflex accent
     &#195;          Capital A, tilde
     &#196;          Capital A, dieresis or umlaut mark
     &#197;          Capital A, ring
     &#198;          Capital AE dipthong (ligature)
     &#199;          Capital C, cedilla
     &#200;          Capital E, grave accent
     &#201;          Capital E, acute accent
     &#202;          Capital E, circumflex accent
     &#203;          Capital E, dieresis or umlaut mark
     &#204;          Capital I, grave accent
     &#205;          Capital I, acute accent
     &#206;          Capital I, circumflex accent
     &#207;          Capital I, dieresis or umlaut mark
     &#208;          Capital Eth, Icelandic
     &#209;          Capital N, tilde
     &#210;          Capital O, grave accent
     &#211;          Capital O, acute accent
     &#212;          Capital O, circumflex accent
     &#213;          Capital O, tilde
     &#214;          Capital O, dieresis or umlaut mark
     &#215;          Multiply sign
     &#216;          Capital O, slash
     &#217;          Capital U, grave accent
     &#218;          Capital U, acute accent
     &#219;          Capital U, circumflex accent
     &#220;          Capital U, dieresis or umlaut mark
     &#221;          Capital Y, acute accent
     &#222;          Capital THORN, Icelandic
     &#223;          Small sharp s, German (sz ligature)
     &#224;          Small a, grave accent
     &#225;          Small a, acute accent
     &#226;          Small a, circumflex accent
     &#227;          Small a, tilde
     &#228;          Small a, dieresis or umlaut mark
     &#229;          Small a, ring
     &#230;          Small ae dipthong (ligature)
     &#231;          Small c, cedilla
     &#232;          Small e, grave accent
     &#233;          Small e, acute accent
     &#234;          Small e, circumflex accent
     &#235;          Small e, dieresis or umlaut mark
     &#236;          Small i, grave accent
     &#237;          Small i, acute accent
     &#238;          Small i, circumflex accent
     &#239;          Small i, dieresis or umlaut mark
     &#240;          Small eth, Icelandic
     &#241;          Small n, tilde
     &#242;          Small o, grave accent
     &#243;          Small o, acute accent
     &#244;          Small o, circumflex accent
     &#245;          Small o, tilde
     &#246;          Small o, dieresis or umlaut mark
     &#247;          Division sign
     &#248;          Small o, slash
     &#249;          Small u, grave accent
     &#250;          Small u, acute accent
     &#251;          Small u, circumflex accent
     &#252;          Small u, dieresis or umlaut mark
     &#253;          Small y, acute accent
     &#254;          Small thorn, Icelandic
     &#255;          Small y, dieresis or umlaut mark

14.2. 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.

14.2.1. 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).

14.2.2. Highlighted Phrase Element


     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.

14.2.3. Plain Text Element


     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:

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

14.2.4. 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>


     <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.

14.3. Proposed Features

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

14.3.1. Additional Character Entities

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

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

14.3.2. 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.

14.3.3. 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.

14.3.4. 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.

15. 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

15.1. 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

     Daniel W.

     Research Technical Staff, W3 Consortium
     MIT Laboratory for Computer Science
     545 Technology Square
     Cambridge, MA 02139, U.S.A.
     Fax: +1 (617) 258 8682