Hypertext Markup Language - 2.0
draft-ietf-html-spec-05

HTML Working Group T. Berners-Lee
INTERNET-DRAFT MIT/W3C
<draft-ietf-html-spec-05.txt> D. Connolly
Expires: In six months August 8, 1995
 Hypertext Markup Language - 2.0
Status of this Memo
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 ABSTRACT
 The Hypertext Markup Language (HTML) is a simple markup language
 used to create hypertext documents that are platform
 independent. HTML documents are SGML documents with generic
 semantics that are appropriate for representing information from
 a wide range of domains. HTML markup can represent hypertext
 news, mail, documentation, and hypermedia; menus of options;
 database query results; simple structured documents with
 in-lined graphics; and hypertext views of existing bodies of
 information.
 HTML has been in use by the World Wide Web (WWW) global
 information initiative since 1990. This specification roughly
 corresponds to the capabilities of HTML in common use prior to
 June 1994. HTML is an application of ISO Standard 8879:1986
 Information Processing Text and Office Systems; Standard
 Generalized Markup Language (SGML).
 The `text/html' Internet Media Type (RFC 1590) and MIME Content
 Type (RFC 1521) is defined by this specification.
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 CONTENTS
 1 Introduction .......................................... 3
 1.1 Scope ................................................. 3
 1.2 Conformance ........................................... 3
 2 Terms ................................................. 5
 3 HTML as an Application of SGML ........................ 9
 3.1 SGML Documents ........................................ 9
 3.2 HTML Lexical Syntax .................................. 11
 3.3 HTML Public Text Identifiers ......................... 15
 3.4 Example HTML Document ................................ 16
 4 HTML as an Internet Media Type ....................... 16
 4.1 text/html media type ................................. 16
 4.2 HTML Document Representation ......................... 17
 5 Document Structure ................................... 18
 5.1 Document Element: HTML ............................... 19
 5.2 Head: HEAD ........................................... 19
 5.3 Body: BODY ........................................... 22
 5.4 Headings: H1 ... H6 .................................. 22
 5.5 Block Structuring Elements ........................... 23
 5.6 List Elements ........................................ 25
 5.7 Phrase Markup ........................................ 28
 5.8 Line Break: BR ....................................... 31
 5.9 Horizontal Rule: HR .................................. 31
 5.10 Image: IMG ........................................... 31
 6 Characters, Words, and Paragraphs .................... 33
 6.1 The HTML Document Character Set ...................... 33
 7 Hyperlinks ........................................... 34
 7.1 Accessing Resources .................................. 34
 7.2 Activation of Hyperlinks ............................. 35
 7.3 Simultaneous Presentation of Image Resources ......... 35
 7.4 Fragment Identifiers ................................. 36
 7.5 Queries and Indexes .................................. 36
 7.6 Image Maps ........................................... 37
 8 Forms ................................................ 37
 8.1 Form Elements ........................................ 37
 8.2 Form Submission ...................................... 42
 9 HTML Public Text ..................................... 45
 9.1 HTML DTD ............................................. 46
 9.2 Strict HTML DTD ...................................... 57
 9.3 Level 1 HTML DTD ..................................... 57
 9.4 Strict Level 1 HTML DTD .............................. 58
 9.5 SGML Declaration for HTML ............................ 59
 9.6 Sample SGML Open Entity Catalog for HTML ............. 61
 9.7 Character Entity Sets ................................ 62
 10 Security Considerations .............................. 64
 11 References ........................................... 64
 12 Acknowledgments ...................................... 66
 12.1 Authors' Addresses ................................... 66
 13 The HTML Coded Character Set ......................... 66
 14 Proposed Entities .................................... 69
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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.
 As HTML is an application of SGML, this specification assumes a
 working knowledge of [SGML].
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'. 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
 aspects of the behavior of HTML user agents.
1.2.1. Documents
 A document is a conforming HTML document if:
 * It is a conforming SGML document, and it conforms to the
 HTML DTD (see 9.1, "HTML DTD").
 NOTE - There are a number of syntactic idioms that
 are not supported or are supported inconsistently in
 some historical user agent implementations. These
 idioms are identified in notes like this throughout
 this specification.
 * It conforms to the application conventions in this
 specification. For example, the value of the HREF attribute
 of the <A> element must conform to the URI syntax.
 * Its document character set includes [ISO-8859-1] and
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 agrees with [ISO-10646]; that is, each code position listed
 in 13, "The HTML Coded Character Set" is included, and each
 code position in the document character set is mapped to the
 same character as [ISO-10646] 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
 [ISO-10646] repertoire. The critical distinction is
 that numeric character references agree with
 [ISO-10646] regardless of how the document is
 encoded.
1.2.2. Feature Test Entities
 The HTML DTD defines a standard HTML document type and several
 variations, by way of feature test entities. Feature test
 entities are declarations in the HTML DTD that control the
 inclusion or exclusion of portions of the DTD.
 HTML.Recommended
 Certain features of the language are necessary for
 compatibility with widespread usage, but they may
 compromise the structural integrity of a document. This
 feature test entity selects a more prescriptive document
 type definition that eliminates those features. It is
 set to `IGNORE' by default.
 For example, in order to preserve the structure of a
 document, an editing user agent may translate HTML
 documents to the recommended subset, or it may require
 that the documents be in the recommended subset for
 import.
 HTML.Deprecated
 Certain features of the language are necessary for
 compatibility with earlier versions of the
 specification, but they tend to be used and implemented
 inconsistently, and their use is deprecated. This
 feature test entity enables a document type definition
 that allows these features. It is set to `INCLUDE' by
 default.
 Documents generated by translation software or editing
 software should not contain deprecated idioms.
1.2.3. User Agents
 An HTML user agent conforms to this specification if:
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 * It parses the characters of an HTML document into data
 characters and markup according to [SGML].
 NOTE - In the interest of robustness and
 extensibility, there are a number of widely deployed
 conventions for handling non-conforming documents.
 See 4.2.1, "Undeclared Markup Error Handling" for
 details.
 * It supports the `ISO-8859-1' character encoding scheme and
 processes each character in the ISO Latin Alphabet No. 1 as
 specified in 6.1, "The HTML Document Character Set".
 NOTE - To support non-western writing systems, HTML
 user agents are encouraged to support
 `ISO-10646-UCS-2' or similar character encoding
 schemes and as much of the character repertoire of
 [ISO-10646] as is practical.
 * It behaves identically for documents whose parsed token
 sequences are identical.
 For example, comments and the whitespace in tags disappear
 during tokenization, and hence they do not influence the
 behavior of conforming user agents.
 * It allows the user to traverse (or at least attempt to
 traverse, resources permitting) all hyperlinks from <A>
 elements in an HTML document.
 An HTML user agent is a level 2 user agent if, additionally:
 * It allows the user to express all form field values
 specified in an HTML document and to (attempt to) submit the
 values as requests to information services.
2. Terms
 absolute URI
 a URI in absolute form; for example, as per [URL]
 anchor
 one of two ends of a hyperlink; typically, a phrase
 marked as an <A> element.
 base URI
 an absolute URI used in combination with a relative URI
 to determine another absolute URI.
 character
 An atom of information, for example a letter or a digit.
 Graphic characters have associated glyphs, where as
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 control characters have associated processing semantics.
 character encoding
 scheme
 A function whose domain is the set of sequences of
 octets, and whose range is the set of sequences of
 characters from a character repertoire; that is, a
 sequence of octets and a character encoding scheme
 determines a sequence of characters.
 character repertoire
 A finite set of characters; e.g. the range of a coded
 character set.
 code position
 An integer. A coded character set and a code position
 from its domain determine a character.
 coded character set
 A function whose domain is a subset of the integers and
 whose range is a character repertoire. That is, for some
 set of integers (usually of the form {0, 1, 2, ..., N}
 ), a coded character set and an integer in that set
 determine a character. Conversely, a character and a
 coded character set determine the character's code
 position (or, in rare cases, a few code positions).
 conforming HTML user
 agent
 A user agent that conforms to this specification in its
 processing of the Internet Media Type `text/html'.
 data character
 Characters other than markup, which make up the content
 of elements.
 document character set
 a coded character set whose range includes all
 characters used in a document. Every SGML document has
 exactly one document character set. Numeric character
 references are resolved via the document character set.
 DTD
 document type definition. Rules that apply SGML to the
 markup of documents of a particular type, including a
 set of element and entity declarations. [SGML]
 element
 A component of the hierarchical structure defined by a
 document type definition; it is identified in a document
 instance by descriptive markup, usually a start-tag and
 end-tag. [SGML]
 end-tag
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 Descriptive markup that identifies the end of an
 element. [SGML]
 entity
 data with an associated notation or interpretation; for
 example, a sequence of octets associated with an
 Internet Media Type. [SGML]
 fragment identifier
 the portion of an HREF attribute value following the `#'
 character which modifies the presentation of the
 destination of a hyperlink.
 form data set
 a sequence of name/value pairs; the names are given by
 an HTML document and the values are given by a user.
 HTML document
 An SGML document conforming to this document type
 definition.
 hyperlink
 a relationship between two anchors, called the tail and
 the head.
 markup
 Syntactically delimited characters added to the data of
 a document to represent its structure. There are four
 different kinds of markup: descriptive markup (tags),
 references, markup declarations, and processing
 instructions. [SGML]
 may
 A document or user interface is conforming whether this
 statement applies or not.
 media type
 an Internet Media Type, as per [IMEDIA].
 message entity
 a head and body. The head is a collection of name/value
 fields, and the body is a sequence of octets. The head
 defines the content type and content transfer encoding
 of the body. [MIME]
 minimally conforming
 HTML user agent
 A user agent that conforms to this specification except
 for form processing. It may only process level 1 HTML
 documents.
 must
 Documents or user agents in conflict with this statement
 are not conforming.
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 numeric character
 reference
 markup that refers to a character by its code position
 in the document character set.
 SGML document
 A sequence of characters organized physically as a set
 of entities and logically into a hierarchy of elements.
 An SGML document consists of data characters and markup;
 the markup describes the structure of the information
 and an instance of that structure. [SGML]
 shall
 If a document or user agent conflicts with this
 statement, it does not conform to this specification.
 should
 If a document or user agent conflicts with this
 statement, undesirable results may occur in practice
 even though it conforms to this specification.
 start-tag
 Descriptive markup that identifies the start of an
 element and specifies its generic identifier and
 attributes. [SGML]
 syntax-reference
 character set
 A coded character set whose range includes all
 characters used for markup; e.g. name characters and
 delimiter characters.
 tag
 Markup that delimits an element. A tag includes a name
 which refers to an element declaration in the DTD, and
 may include attributes. [SGML]
 text entity
 A finite sequence of characters. A text entity typically
 takes the form of a sequence of octets with some
 associated character encoding scheme, transmitted over
 the network or stored in a file. [SGML]
 typical
 Typical processing is described for many elements. This
 is not a mandatory part of the specification but is
 given as guidance for designers and to help explain the
 uses for which the elements were intended.
 URI
 A Uniform Resource Identifier is a formatted string that
 serves as an identifier for a resource, typically on the
 Internet. URIs are used in HTML to identify the anchors
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 of hyperlinks. URIs in common practice include Uniform
 Resource Locators (URLs)[URL] and Relative URLs
 [RELURL].
 user agent
 A component of a distributed system that presents an
 interface and processes requests on behalf of a user;
 for example, a www browser or a mail user agent.
 WWW
 The World-Wide Web is a hypertext-based, distributed
 information system created by researchers at CERN in
 Switzerland. <URL:http://www.w3.org/>
3. HTML as an Application of SGML
 HTML is an application of ISO 8879:1986 -- Standard Generalized
 Markup Language (SGML). SGML is a system for defining structured
 document types and markup languages to represent instances of
 those document types[SGML]. The public text -- DTD and SGML
 declaration -- of the HTML document type definition are provided
 in 9, "HTML Public Text".
 The term _HTML_ refers to both the document type defined here
 and the markup language for representing instances of this
 document type.
3.1. 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.
 In the SGML specification, the first production of the SGML
 syntax 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
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 concrete syntax determines how the sequence of characters of the
 document is mapped to a sequence of terminals in the grammar of
 the prologue.
 For example, consider the following document:
 <!DOCTYPE html PUBLIC "-//IETF//DTD HTML 2.0//EN">
 <title>Parsing Example</title>
 <p>Some text. <em>&#42;wow&#42;</em></p>
 An HTML user agent should use the SGML declaration that is given
 in 9.5, "SGML Declaration for HTML". According to its document
 character set, `&#42;' refers to an asterisk character, `*'.
 The instance above is regarded as the following sequence of
 terminals:
 1. start-tag: TITLE
 2. data characters: ``Parsing Example''
 3. end-tag: TITLE
 4. start-tag: P
 5. data characters ``Some text. ''
 6. start-tag: EM
 7. data characters: ``*wow*''
 8. end-tag: EM
 9. end-tag: P
 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' (9.1, "HTML DTD"). The terminals above parse as:
 HTML
 |
 \-HEAD
 | |
 | \-TITLE
 | |
 | \-<TITLE>
 | |
 | \-"Parsing Example"
 | |
 | \-</TITLE>
 |
 \-BODY
 |
 \-P
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 |
 \-<P>
 |
 \-"Some text. "
 |
 \-EM
 | |
 | \-<EM>
 | |
 | \-"*wow*"
 | |
 | \-</EM>
 |
 \-</P>
 Some of the elements are delimited explicity by tags, while the
 boundaries of others are inferred. The <HTML> element contains a
 <HEAD> element and a <BODY> element. The <HEAD> contains
 <TITLE>, which is explicitly delimited by start- and end-tags.
3.2. HTML Lexical Syntax
 SGML specifies an abstract syntax and a reference concrete
 syntax. Aside from certain quantities and capacities (e.g. the
 limit on the length of a name), all HTML documents use the
 reference concrete syntax. In particular, all markup characters
 are in the repertoire of [ISO-646]. Data characters are drawn
 from the document character set (see 6, "Characters, Words, and
 Paragraphs").
 A complete discussion of SGML parsing, e.g. the mapping of a
 sequence of characters to a sequence of tags and data, is left
 to the SGML standard[SGML]. This section is only a summary.
3.2.1. 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 map to
 single-character strings, via the document character set. Each
 reference to one of the general entities defined in the HTML DTD
 maps to a single-character string.
 For example,
 abc&lt;def => "abc","<","def"
 abc&#60;def => "abc","<","def"
 The terminating semicolon on entity or numeric character
 references is only necessary when the character following the
 reference would otherwise be recognized as part of the name (see
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 9.4.5 ``Reference End'' in [SGML]).
 abc &lt def => "abc ","<"," def"
 abc &#60 def => "abc ","<"," def"
 An ampersand is only recognized as markup when it is followed by
 a letter or a `#' and a digit:
 abc & lt def => "abc & lt def"
 abc &# 60 def => "abc &# 60 def"
 A useful technique for translating plain text to HTML is to
 replace each '<', '&', and '>' by an entity reference or numeric
 character reference as follows:
 ENTITY NUMERIC
 CHARACTER REFERENCE CHAR REF CHARACTER DESCRIPTION
 --------- ---------- ----------- ---------------------
 & &amp; &#38; Ampersand
 < &lt; &#60; Less than
 > &gt; &#62; Greater than
 NOTE - There are SGML mechanisms, CDATA and RCDATA
 declared content, that allow most `<', `>', and `&'
 characters to be entered without the use of entity
 references. Because these mechanisms tend to be used and
 implemented inconsistently, and because they conflict
 with techniques for reducing HTML to 7 bit ASCII for
 transport, they are deprecated in this version of HTML.
 See 5.5.2.1, "Example and Listing: XMP, LISTING".
3.2.2. 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, 9.1, "HTML DTD" for
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 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.
3.2.3. Names
 A name consists of a letter followed by letters, digits,
 periods, or hyphens. The length of a name is limited to 72
 characters by the `NAMELEN' parameter in the SGML delcaration
 for HTML, 9.5, "SGML Declaration for HTML". Element and
 attribute 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 `<'.
3.2.4. Attributes
 In a start-tag, white space and attributes are allowed between
 the element name and the closing delimiter. An attribute
 specification typically consists of an attribute name, an equal
 sign, and a value, though some attribute specifications may be
 just a name token. White space is allowed around the equal sign.
 The value of the attribute may be either:
 * A string literal, delimited by single quotes or double
 quotes and not containing any occurrences of the delimiting
 character.
 NOTE - Some historical implementations consider any
 occurrence of the `>' character to signal the end of
 a tag. For compatibility with such implementations,
 when `>' appears in an attribute value, it should be
 represented with a numeric character reference. For
 example, `<IMG SRC="eq1.jpg" alt="a>b">' should be
 written `<IMG SRC="eq1.jpg" alt="a&#62;b">' or `<IMG
 SRC="eq1.jpg" alt="a&gt;b">'.
 * A name token (a sequence of letters, digits, periods, or
 hyphens). Name tokens are not case sensitive.
 NOTE - Some historical implementations allow any
 character except space or `>' in a name token.
 In this example, <img> is the element name, src is the attribute
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 name, and `http://host/dir/file.gif' is the attribute value:
 <img src='http://host/dir/file.gif'>
 A useful technique for computing an attribute value literal for
 a given string is to replace each quote and white space
 character by an entity reference or numeric character reference
 as follows:
 ENTITY NUMERIC
 CHARACTER REFERENCE CHAR REF CHARACTER DESCRIPTION
 --------- ---------- ----------- ---------------------
 HT &#9; Tab
 LF &#10; Line Feed
 CR &#13; Carriage Return
 SP &#32; Space
 " &quot; &#34; Quotation mark
 & &amp; &#38; Ampersand
 For example:
 <IMG SRC="image.jpg" alt="First &quot;real&quot; example">
 The `NAMELEN' parameter in the SGML declaration (9.5, "SGML
 Declaration for HTML") limits the length of an attribute value
 to 1024 characters.
 Attributes such as ISMAP and COMPACT may be written using a
 minimized syntax (see 7.9.1.2 ``Omitted Attribute Name'' in
 [SGML]). The markup:
 <UL COMPACT="compact">
 can be written using a minimized syntax:
 <UL COMPACT>
 NOTE - Some historical implementations only understand
 the minimized syntax.
3.2.5. Comments
 To include comments in an HTML document, use a comment
 declaration. A comment declaration consists of `<!' followed by
 zero or more comments followed by `>'. Each comment starts with
 `--' and includes all text up to and including the next
 occurrence of `--'. In a comment declaration, white space is
 allowed after each comment, but not before the first comment.
 The entire comment declaration is ignored.
 NOTE - Some historical HTML implementations incorrectly
 consider any `>' character to be the termination of a
 comment.
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 For example:
 <!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN">
 <HEAD>
 <TITLE>HTML Comment Example</TITLE>
 <!-- Id: html-sgml.sgm,v 1.5 1995年05月26日 21:29:50 connolly Exp -->
 <!-- another -- -- comment -->
 <!>
 </HEAD>
 <BODY>
 <p> <!- not a comment, just regular old data characters ->
3.3. HTML Public Text Identifiers
 To identify information as an HTML document conforming to this
 specification, each document must start with one of the
 following document type declarations.
 <!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN">
 This document type declaration refers to the HTML DTD in 9.1,
 "HTML DTD".
 NOTE - If the body of a `text/html' message entity does
 not begin with a document type declaration, an HTML user
 agent should infer the above document type declaration.
 <!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0 Level 2//EN">
 This document type declaration also refers to the HTML DTD which
 appears in 9.1, "HTML DTD".
 <!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0 Level 1//EN">
 This document type declaration refers to the level 1 HTML DTD in
 9.3, "Level 1 HTML DTD". Form elements must not occur in level 1
 documents.
 <!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0 Strict//EN">
 <!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0 Strict Level 1//EN">
 These two document type declarations refer to the HTML DTD in
 9.2, "Strict HTML DTD" and 9.4, "Strict Level 1 HTML DTD". They
 refer to the more structurally rigid definition of HTML.
 HTML user agents may support other document types. In
 particular, they may support other formal public identifiers, or
 other document types altogether. They may support an internal
 declaration subset with supplemental entity, element, and other
 markup declarations.
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3.4. Example HTML Document
 <!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN">
 <HTML>
 <!-- Here's a good place to put a comment. -->
 <HEAD>
 <TITLE>Structural Example</TITLE>
 </HEAD><BODY>
 <H1>First Header</H1>
 <P>This is a paragraph in the example HTML file. Keep in mind
 that the title does not appear in the document text, but that
 the header (defined by H1) does.</P>
 <OL>
 <LI>First item in an ordered list.
 <LI>Second item in an ordered list.
 <UL COMPACT>
 <LI> Note that lists can be nested;
 <LI> Whitespace may be used to assist in reading the
 HTML source.
 </UL>
 <LI>Third item in an ordered list.
 </OL>
 <P>This is an additional paragraph. Technically, end tags are
 not required for paragraphs, although they are allowed. You can
 include character highlighting in a paragraph. <EM>This sentence
 of the paragraph is emphasized.</EM> Note that the &lt;/P&gt;
 end tag has been omitted.
 <P>
 <IMG SRC ="triangle.xbm" alt="Warning: ">
 Be sure to read these <b>bold instructions</b>.
 </BODY></HTML>
4. HTML as an Internet Media Type
 An HTML user agent allows users to interact with resources which
 have HTML representations. At a minimum, it must allow users to
 examine and navigate the content of HTML level 1 documents. HTML
 user agents should be able to preserve all formatting
 distinctions represented in an HTML document, and be able to
 simultaneously present resources referred to by IMG elements
 (they may ignore some formatting distinctions or IMG resources
 at the request of the user). Level 2 HTML user agents should
 support form entry and submission.
4.1. text/html media type
 This specification defines the Internet Media Type[IMEDIA]
 (formerly referred to as the Content Type[MIME]) called
 `text/html'. The following is to be registered with [IANA].
 Media Type name
 text
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 Media subtype name
 html
 Required parameters
 none
 Optional parameters
 level, charset
 Encoding considerations
 any encoding is allowed
 Security considerations
 see 10, "Security Considerations"
 The optional parameters are defined as follows:
 Level
 The level parameter specifies the feature set used in
 the document. The level is an integer number, implying
 that any features of same or lower level may be present
 in the document. Level 1 is all features defined in this
 specification except those that require the <FORM>
 element. Level 2 includes form processing. Level 2 is
 the default.
 Charset
 The charset parameter (as defined in section 7.1.1 of
 RFC 1521[MIME]) may be given to specify the character
 encoding scheme used to represent the HTML document as a
 sequence of octets. The default value is outside the
 scope of this specification; but for example, the
 default is `US-ASCII' in the context of MIME mail, and
 `ISO-8859-1' in the context of HTTP.
4.2. 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.
4.2.1. 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
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 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; &amp; &beta; be finite sets.
 => "Let &alpha; & &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 does
 not conform to this specification.
4.2.2. Conventional Representation of Newlines
 SGML specifies that a text entity is a sequence of records, each
 beginning with a record start character and ending with a record
 end character (code positions 10 and 13 respectively) (section
 7.6.1, ``Record Boundaries'' in [SGML]).
 [MIME] specifies that a body of type `text/*' is a sequence of
 lines, each terminated by CRLF, that is, octets 13, 10.
 In practice, HTML documents are frequently represented and
 transmitted using an end of line convention that depends on the
 conventions of the source of the document; frequently, that
 representation consists of CR only, LF only, or a CR LF
 sequence. Hence the decoding of the octets will often result in
 a text entity with some missing record start and record end
 characters.
 Since there is no ambiguity, HTML user agents are encouraged to
 infer the missing record start and end characters.
 An HTML user agent should treat end of line in any of its
 variations as a word space in all contexts except preformatted
 text. Within preformatted text, an HTML user agent should treat
 any of the three common representations of end-of-line as
 starting a new line.
5. Document Structure
 An HTML document is a tree of elements, including a head and
 body, headings, paragraphs, lists, etc. Form elements are
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 discussed in 8, "Forms".
5.1. Document Element: HTML
 The HTML document element consists of a head and a body, much
 like a memo or a mail message. The head contains the title and
 optional elements. The body is a text flow consisting of
 paragraphs, lists, and other elements.
5.2. Head: HEAD
 The head of an HTML document is an unordered collection of
 information about the document. For example:
 <!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN">
 <HEAD>
 <TITLE>Introduction to HTML</TITLE>
 </HEAD>
 ...
5.2.1. Title: TITLE
 Every HTML document must contain a <TITLE> element.
 The title should identify the contents of the document in a
 global context. A short title, such as ``Introduction'' may be
 meaningless out of context. A title such as ``Introduction to
 HTML Elements'' is more appropriate.
 NOTE - The length of a title is not limited; however,
 long titles may be truncated in some applications. To
 minimize this possibility, titles should be fewer than
 64 characters.
 A user agent may display the title of a document in a history
 list or as a label for the window displaying the document. This
 differs from headings (5.4, "Headings: H1 ... H6"), which are
 typically displayed within the body text flow.
5.2.2. Base Address: BASE
 The optional <BASE> element allows the address of a document to
 be recorded in situations in which the document may be read out
 of context. The required HREF attribute specifies the base URI
 (see 7, "Hyperlinks") for navigating the document, overriding
 any context otherwise known to the user agent. The value of the
 HREF attribute must be an absolute URI.
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5.2.3. Keyword Index: ISINDEX
 The <ISINDEX> element indicates that the user agent should allow
 the user to search an index by giving keywords. See 7.5,
 "Queries and Indexes" for details.
5.2.4. Link: LINK
 The <LINK> element represents a hyperlink (see 7, "Hyperlinks").
 It has the same attributes as the <A> element (see 5.7.3,
 "Anchor: A").
 The <LINK> element is typically used to indicate authorship,
 related indexes and glossaries, older or more recent versions,
 style sheets, document hierarchy etc.
5.2.5. Associated Meta-information: META
 The <META> element is an extensible container for use in
 identifying specialized document meta-information.
 Meta-information has two main functions:
 * to provide a means to discover that the data set exists
 and how it might be obtained or accessed; and
 * to document the content, quality, and features of a data
 set, indicating its fitness for use.
 Each <META> element specifies a name/value pair. If multiple
 META elements are provided with the same name, their combined
 contents--concatenated as a comma-separated list--is the value
 associated with that name.
 NOTE - The <META> element should not be used where a
 specific element, such as <TITLE>, would be more
 appropriate.
 HTTP servers may read the content of the document <HEAD> to
 generate header fields corresponding to any elements defining a
 value for the attribute HTTP-EQUIV.
 NOTE - The method by which the server extracts document
 meta-information is unspecified and not mandatory. The
 <META> element only provides an extensible mechanism for
 identifying and embedding document meta-information --
 how it may be used is up to the individual server
 implementation and the HTML user agent.
 Attributes of the META element:
 HTTP-EQUIV
 binds the element to an HTTP header field. An HTTP
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 server may use this information to process the document.
 In particular, it may include a header field in the
 responses to requests for this document: the header name
 is taken from the HTTP-EQUIV attribute value, and the
 header value is taken from the value of the CONTENT
 attribute. HTTP header names are not case sensitive.
 NAME
 specifies the name of the name/value pair. If not
 present, HTTP-EQUIV gives the name.
 CONTENT
 specifies the value of the name/value pair.
 Examples
 If the document contains:
 <META HTTP-EQUIV="Expires"
 CONTENT="1993年12月04日 21:29:02 GMT">
 <meta http-equiv="Keywords" CONTENT="Fred">
 <META HTTP-EQUIV="Reply-to"
 content="fielding@ics.uci.edu (Roy Fielding)">
 <Meta Http-equiv="Keywords" CONTENT="Barney">
 then the server may include the following header fields:
 Expires: 1993年12月04日 21:29:02 GMT
 Keywords: Fred, Barney
 Reply-to: fielding@ics.uci.edu (Roy Fielding)
 as part of the HTTP response to a `GET' or `HEAD' request for
 that document.
 An HTTP server must not use the <META> element to form an HTTP
 response header unless the HTTP-EQUIV attribute is present.
 An HTTP server may disregard any <META> elements that specify
 information controlled by the HTTP server, for example `Server',
 `Date', and `Last-modified'.
5.2.6. Next Id: NEXTID
 The <NEXTID> element is included for historical reasons only.
 HTML document should not contain <NEXTID> elements.
 The <NEXTID> element gives a hint for the name to use for a new
 <A> element when editing an HTML document. It should be distinct
 from all NAME attribute values on <A> elements. For example:
 <NEXTID N=Z27>
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5.3. Body: BODY
 The <BODY> element contains the text flow of the document,
 including headings, paragraphs, lists, etc.
 For example:
 <BODY>
 <h1>Important Stuff</h1>
 <p>Explanation about important stuff...
 </BODY>
5.4. Headings: H1 ... H6
 The six heading elements, <H1> through <H6>, denote section
 headings. Although the order and occurrence of headings is not
 constrained by the HTML DTD, documents should not skip levels
 (for example, from H1 to H3), as converting such documents to
 other representations is often problematic.
 Example of use:
 <H1>This is a heading</H1>
 Here is some text
 <H2>Second level heading</H2>
 Here is some more text.
 Typical renderings are:
 H1
 Bold, very-large font, centered. One or two blank lines
 above and below.
 H2
 Bold, large font, flush-left. One or two blank lines
 above and below.
 H3
 Italic, large font, slightly indented from the left
 margin. One or two blank lines above and below.
 H4
 Bold, normal font, indented more than H3. One blank line
 above and below.
 H5
 Italic, normal font, indented as H4. One blank line
 above.
 H6
 Bold, indented same as normal text, more than H5. One
 blank line above.
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5.5. Block Structuring Elements
 Block structuring elements include paragraphs, lists, and block
 quotes. They must not contain heading elements, but they may
 contain phrase markup, and in some cases, they may be nested.
5.5.1. Paragraph: P
 The <P> element indicates a paragraph. The exact indentation,
 leading space, etc. of a paragraph is not specified and may be a
 function of other tags, style sheets, etc.
 Typically, paragraphs are surrounded by a vertical space of one
 line or half a line. The first line in a paragraph is indented
 in some cases.
 Example of use:
 <H1>This Heading Precedes the Paragraph</H1>
 <P>This is the text of the first paragraph.
 <P>This is the text of the second paragraph. Although you do not
 need to start paragraphs on new lines, maintaining this
 convention facilitates document maintenance.</P>
 <P>This is the text of a third paragraph.</P>
5.5.2. Preformatted Text: PRE
 The <PRE> element represents a character cell block of text and
 is suitable for text that has been formatted for a monospaced
 font.
 The <PRE> tag may be used with the optional WIDTH attribute. The
 WIDTH attribute specifies the maximum number of characters for a
 line and allows the HTML user agent to select a suitable font
 and indentation.
 Within preformatted text:
 * Line breaks within the text are rendered as a move to the
 beginning of the next line.
 NOTE - References to the ``beginning of a new line''
 do not imply that the renderer is forbidden from
 using a constant left indent for rendering
 preformatted text. The left indent may be
 constrained by the width required.
 * Anchor elements and phrase markup may be used.
 NOTE - Constraints on the processing of <PRE>
 content may may limit or prevent the ability of the
 HTML user agent to faithfully render phrase markup.
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 * Elements that define paragraph formatting (headings,
 address, etc.) must not be used.
 NOTE - Some historical documents contain <P> tags in
 <PRE> elements. User agents are encouraged to treat
 this as a line break. A <P> tag followed by a
 newline character should produce only one line
 break, not a line break plus a blank line.
 * The horizontal tab character (code position 9 in the HTML
 document character set) 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.
 Documents should not contain tab characters, as they are not
 supported consistently.
 Example of use:
 <PRE>
 Line 1.
 Line 2 is to the right of line 1. <a href="abc">abc</a>
 Line 3 aligns with line 2. <a href="def">def</a>
 </PRE>
5.5.2.1. Example and Listing: XMP, LISTING
 The <XMP> and <LISTING> elements are similar to the <PRE>
 element, but they have a different syntax. Their content is
 declared as CDATA, which means that no markup except the end-tag
 open delimiter-in-context is recognized (see 9.6 ``Delimiter
 Recognition'' of [SGML]).
 NOTE - In a previous draft of the HTML specification,
 the syntax of <XMP> and <LISTING> elements allowed
 closing tags to be treated as data characters, as long
 as the tag name was not <XMP> or <LISTING>,
 respectively.
 Since CDATA declared content has a number of unfortunate
 interactions with processing techniques and tends to be used and
 implemented inconsistently, HTML documents should not contain
 <XMP> nor <LISTING> elements -- the <PRE> tag is more expressive
 and more consistently supported.
 The <LISTING> element should be rendered so that at least 132
 characters fit on a line. The <XMP> element should be rendered
 so that at least 80 characters fit on a line but is otherwise
 identical to the <LISTING> element.
 NOTE - In a previous draft, HTML included a <PLAINTEXT>
 element that is similar to the <LISTING> element, except
 that there is no closing tag: all characters after the
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 <PLAINTEXT> start-tag are data.
5.5.3. Address: ADDRESS
 The <ADDRESS> element contains such information as address,
 signature and authorship, often at the beginning or end of the
 body of a document.
 Typically, the <ADDRESS> element is rendered in an italic
 typeface and may be indented.
 Example of use:
 <ADDRESS>
 Newsletter editor<BR>
 J.R. Brown<BR>
 JimquickPost News, Jimquick, CT 01234<BR>
 Tel (123) 456 7890
 </ADDRESS>
5.5.4. Block Quote: BLOCKQUOTE
 The <BLOCKQUOTE> element contains text quoted from another
 source.
 A typical rendering might be a slight extra left and right
 indent, and/or italic font. The <BLOCKQUOTE> typically provides
 space above and below the quote.
 Single-font rendition may reflect the quotation style of
 Internet mail by putting a vertical line of graphic characters,
 such as the greater than symbol (>), in the left margin.
 Example of use:
 I think the poem ends
 <BLOCKQUOTE>
 <P>Soft you now, the fair Ophelia. Nymph, in thy orisons, be all
 my sins remembered.
 </BLOCKQUOTE>
 but I am not sure.
5.6. List Elements
 HTML includes a number of list elements. They may be used in
 combination; for example, a <OL> may be nested in an <LI>
 element of a <UL>.
 The COMPACT attribute suggests that a compact rendering be used.
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5.6.1. Unordered List: UL, LI
 The <UL> represents a list of items -- typically a bulleted
 list.
 The content of a <UL> element is a sequence of <LI> elements.
 For example:
 <UL>
 <LI>First list item
 <LI>Second list item
 <p>second paragraph of second item
 <LI>Third list item
 </UL>
5.6.2. Ordered List: OL
 The <OL> element represents an ordered list of items, sorted by
 sequence or order of importance. It is typically rendered as a
 numbered list.
 The content of a <OL> element is a sequence of <LI> elements.
 For example:
 <OL>
 <LI>Click the Web button to open URI window.
 <LI>Enter the URI number in the text field of the Open URI
 window. The Web document you specified is displayed.
 <ol>
 <li>substep 1
 <li>substep 2
 </ol>
 <LI>Click highlighted text to move from one link to another.
 </OL>
5.6.3. Directory List: DIR
 The <DIR> element is similar to the <UL> element. It represents
 a list of short items, typically up to 20 characters each. Items
 in a directory list may be arranged in columns, typically 24
 characters wide.
 The content of a <DIR> element is a sequence of <LI> elements.
 Nested block elements are not allowed in the content of <DIR>
 elements. For example:
 <DIR>
 <LI>A-H<LI>I-M
 <LI>M-R<LI>S-Z
 </DIR>
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5.6.4. Menu List: MENU
 The <MENU> element is a list of items with typically one line
 per item. The menu list style is typically more compact than the
 style of an unordered list.
 The content of a <MENU> element is a sequence of <LI> elements.
 Nested block elements are not allowed in the content of <MENU>
 elements. For example:
 <MENU>
 <LI>First item in the list.
 <LI>Second item in the list.
 <LI>Third item in the list.
 </MENU>
5.6.5. Definition List: DL, DT, DD
 A definition list is a list of terms and corresponding
 definitions. Definition lists are typically formatted with the
 term flush-left and the definition, formatted paragraph style,
 indented after the term.
 The content of a <DL> element is a sequence of <DT> elements
 and/or <DD> elements, usually in pairs. Multiple <DT> may be
 paired with a single <DD> element. Documents should not contain
 multiple consecutive <DD> elements.
 Example of use:
 <DL>
 <DT>Term<DD>This is the definition of the first term.
 <DT>Term<DD>This is the definition of the second term.
 </DL>
 If the DT term does not fit in the DT column (typically one
 third of the display area), it may be extended across the page
 with the DD section moved to the next line, or it may be wrapped
 onto successive lines of the left hand column.
 The optional COMPACT attribute suggests that a compact rendering
 be used, because the list items are small and/or the entire list
 is large.
 Unless the COMPACT attribute is present, an HTML user agent may
 leave white space between successive DT, DD pairs. The COMPACT
 attribute may also reduce the width of the left-hand (DT)
 column.
 <DL COMPACT>
 <DT>Term<DD>This is the first definition in compact format.
 <DT>Term<DD>This is the second definition in compact format.
 </DL>
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5.7. Phrase Markup
 Phrases may be marked up according to idiomatic usage,
 typographic appearance, or for use as hyperlink anchors.
 User agents must render highlighted phrases distinctly from
 plain text. Additionally, <EM> content must be rendered as
 distinct from <STRONG> content, and <B> content must rendered as
 distinct from <I> content.
 Phrase elements may be nested within the content of other phrase
 elements; however, HTML user agents may render nested phrase
 elements indistinctly from non-nested elements:
 plain <B>bold <I>italic</I></B> may be rendered
 the same as plain <B>bold </B><I>italic</I>
5.7.1. Idiomatic Elements
 Phrases may be marked up to indicate certain idioms.
 NOTE - User agents may support the <DFN> element, not
 included in this specification, as it has been deployed
 to some extent. It is used to indicate the defining
 instance of a term, and it is typically rendered in
 italic or bold italic.
5.7.1.1. Citation: CITE
 The <CITE> element is used to indicate the title of a book or
 other citation. It is typically rendered as italics. For
 example:
 He just couldn't get enough of <cite>The Grapes of Wrath</cite>.
5.7.1.2. Code: CODE
 The <CODE> element indicates an example of code, typically
 rendered in a mono-spaced font. The <CODE> element is intended
 for short words or phrases of code; the <PRE> block structuring
 element (5.5.2, "Preformatted Text: PRE") is more apropriate for
 multiple-line listings. For example:
 The expression <code>x += 1</code>
 is short for <code>x = x + 1</code>.
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5.7.1.3. Emphasis: EM
 The <EM> element indicates an emphasized phrase, typically
 rendered as italics. For example:
 A singular subject <em>always</em> takes a singular verb.
5.7.1.4. Keyboard: KBD
 The <KBD> element indicates text typed by a user, typically
 rendered in a mono-spaced font. This is commonly used in
 instruction manuals. For example:
 Enter <kbd>FIND IT</kbd> to search the database.
5.7.1.5. Sample: SAMP
 The <SAMP> element indicates a sequence of literal characters,
 typically rendered in a mono-spaced font. For example:
 The only word containing the letters <samp>mt</samp> is dreamt.
5.7.1.6. Strong Emphasis: STRONG
 The <STRONG> element indicates strong emphasis, typically
 rendered in bold. For example:
 <strong>STOP</strong>, or I'll say "<strong>STOP</strong>" again!.
5.7.1.7. Variable: VAR
 The <VAR> element indicates a placeholder variable, typically
 rendered as italic. For example:
 Type <SAMP>html-check <VAR>file</VAR> | more</SAMP>
 to check <VAR>file</VAR> for markup errors.
5.7.2. Typographic Elements
 Typographic elements are used to specify the format of marked
 text.
 Typical renderings for idiomatic elements may vary between user
 agents. If a specific rendering is necessary -- for example,
 when referring to a specific text attribute as in ``The italic
 parts are mandatory'' -- a typographic element can be used to
 ensure that the intended typography is used where possible.
 NOTE - User agents may support some typographic elements
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 not included in this specification, as they have been
 deployed to some extent. The <STRIKE> element indicates
 horizontal line through the characters, and the <U>
 element indicates an underline.
5.7.2.1. Bold: B
 The <B> element indicates bold text. Where bold typography is
 unavailable, an alternative representation may be used.
5.7.2.2. Italic: I
 The <I> element indicates italic text. Where italic typography
 is unavailable, an alternative representation may be used.
5.7.2.3. Teletype: TT
 The <TT> element indicates teletype (monospaced )text. Where a
 teletype font is unavailable, an alternative representation may
 be used.
5.7.3. Anchor: A
 The <A> element indicates a hyperlink anchor (see 7,
 "Hyperlinks"). At least one of the NAME and HREF attributes
 should be present. Attributes of the <A> element:
 HREF
 gives the URI of the head anchor of a hyperlink.
 NAME
 gives the name of the anchor, and makes it available as
 a head of a hyperlink.
 TITLE
 suggests a title for the destination resource --
 advisory only. The TITLE attribute may be used:
 * for display prior to accessing the destination
 resource, for example, as a margin note or on a
 small box while the mouse is over the anchor, or
 while the document is being loaded;
 * for resources that do not include a title, such as
 graphics, plain text and Gopher menus, for use as a
 window title.
 REL
 The REL attribute gives the relationship(s) described by
 the hyperlink. The value is a whitespace separated list
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 of relationship names.
 REV
 same as the REL attribute, but the semantics of the
 relationship are in the reverse direction. A link from A
 to B with REL=``X'' expresses the same relationship as a
 link from B to A with REV=``X''. An anchor may have both
 REL and REV attributes.
 URN
 specifies a preferred, more persistent identifier for
 the head anchor of the hyperlink. The syntax and
 semantics of the URN attribute are not yet specified.
 METHODS
 specifies methods to be used in accessing the
 destination, as a whitespace-separated list of names.
 The set of applicable names is a function of the scheme
 of the URI in the HREF attribute. For similar reasons as
 for the TITLE attribute, it may be useful to include the
 information in advance in the link. For example, the
 HTML user agent may chose a different rendering as a
 function of the methods allowed; for example, something
 that is searchable may get a different icon.
5.8. Line Break: BR
 The <BR> element specifies a line break between words (see 6,
 "Characters, Words, and Paragraphs"). For example:
 <P> Pease porridge hot<BR>
 Pease porridge cold<BR>
 Pease porridge in the pot<BR>
 Nine days old.
5.9. Horizontal Rule: HR
 The <HR> element is a divider between sections of text;
 typically a full width horizontal rule or equivalent graphic.
 For example:
 <HR>
 <ADDRESS>February 8, 1995, CERN</ADDRESS>
 </BODY>
5.10. Image: IMG
 The <IMG> element refers to an image or icon via a hyperlink
 (see 7.3, "Simultaneous Presentation of Image Resources").
 HTML user agents may process the value of the ALT attribute as
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 an alternative to processing the image resource indicated by the
 SRC attribute.
 NOTE - Some HTML user agents can process graphics linked
 via anchors, but not <IMG> graphics. If a graphic is
 essential, it should be referenced from an <A> element
 rather than an <IMG> element. If the graphic is not
 essential, then the <IMG> element is appropriate.
 Attributes of the <IMG> element:
 ALIGN
 alignment of the image with respect to the text
 baseline.
 * `TOP' specifies that the top of the image aligns
 with the tallest item on the line containing the
 image.
 * `MIDDLE' specifies that the center of the image
 aligns with the baseline of the line containing the
 image.
 * `BOTTOM' specifies that the bottom of the image
 aligns with the baseline of the line containing the
 image.
 ALT
 text to use in place of the referenced image resource,
 for example due to processing constraints or user
 preference.
 ISMAP
 indicates an image map (see 7.6, "Image Maps").
 SRC
 specifies the URI of the image resource.
 NOTE - In practice, the media types of image
 resources are limited to a few raster graphic
 formats: typically `image/gif', `image/jpeg'. In
 particular, `text/html' resources are not
 intended to be used as image resources.
 Examples of use:
 <IMG SRC="triangle.xbm" ALT="Warning:"> Be sure
 to read these instructions.
 <a href="http://machine/htbin/imagemap/sample">
 <IMG SRC="sample.xbm" ISMAP>
 </a>
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6. Characters, Words, and Paragraphs
 An HTML user agent should present the body of an HTML document
 as a collection of typeset paragraphs and preformatted text.
 Except for preformatted elements (<PRE>, <XMP>, <LISTING>,
 <TEXTAREA>), each block structuring element is regarded as a
 paragraph by taking the data characters in its content and the
 content of its descendant elements, concatenating them, and
 splitting the result into words, separated by space, tab, or
 record end characters (and perhaps hyphen characters). The
 sequence of words is typeset as a paragraph by breaking it into
 lines.
6.1. The HTML Document Character Set
 The document character set specified in 9.5, "SGML Declaration
 for HTML" must be supported by HTML user agents. It includes the
 graphic characters of Latin Alphabet No. 1, or simply Latin-1.
 Latin-1 comprises 191 graphic characters, including the
 alphabets of most Western European languages.
 NOTE - Use the non-breaking space and soft hyphen
 indicator characters is discouraged because support for
 them is not widely deployed.
 NOTE - To support non-western writing systems, a larger
 character repertoire will be specified in a future
 version of HTML. The document character set will be
 [ISO-10646], or some subset that agrees with
 [ISO-10646]; in particular, all numeric character
 references must use code positions assigned by
 [ISO-10646].
 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 the HTML
 document character set only three control characters are
 allowed: Horizontal Tab, Carriage Return, and Line Feed (code
 positions 9, 13, and 10).
 The HTML DTD references the Added Latin 1 entity set, to allow
 mnemonic representation of selected Latin 1 characters using
 only the widely supported ASCII character repertoire. For
 example:
 Kurt G&ouml;del was a famous logician and mathematician.
 See 9.7.2, "ISO Latin 1 Character Entity Set" for a table of the
 ``Added Latin 1'' entities, and 13, "The HTML Coded Character
 Set" for a table of the code positions of [ISO 8859-1] and the
 control characters in the HTML document character set.
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7. Hyperlinks
 In addition to general purpose elements such as paragraphs and
 lists, HTML documents can express hyperlinks. An HTML user agent
 allows the user to navigate these hyperlinks.
 A hyperlink is a relationship between two anchors, called the
 head and the tail of the hyperlink[DEXTER]. Each anchor is
 addressed, or uniquely identified, by an absolute Uniform
 Resource Identifier (URI), optionally followed by a '#' and a
 sequence of characters called a fragment identifier, as per
 [RELURL]. For example:
 http://www.w3.org/hypertext/WWW/TheProject.html
 http://www.w3.org/hypertext/WWW/TheProject.html#z31
 In an anchor address, the URI refers to a resource; it may be
 used in a variety of information retrieval protocols to obtain
 an entity that represents the resource, such as an HTML
 document. The fragment identifier, if present, refers to some
 view on, or portion of the resource.
 An HTML user agent begins navigation with an absolute URI,
 called the base URI, and an HTML document that is a
 representation of the resource identified by the base URI.
 Each of the following markup constructs indicates the tail
 anchor of a hyperlink or set of hyperlinks:
 * <A> elements with HREF present.
 * <LINK> elements.
 * <IMG> elements.
 * <INPUT> elements with the SRC attribute present.
 * <ISINDEX> elements.
 * <FORM> elements with `METHOD=GET'.
 These markup constructs refer to head anchors either directly by
 means of an absolute URI, or indirectly by means of a relative
 URI, which must be combined with the base URI as in [RELURL] to
 determine the address of the head anchor. The markup may also
 include fragment identifiers, separated from the URI by a '#'
 character.
7.1. Accessing Resources
 Once the address of the head anchor is determined, the user
 agent may obtain a representation of the resource, for example
 as in [URL].
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 For example, if the base URI is `http://host/x/y.html' and the
 document contains:
 <img src="../icons/abc.gif">
 then the user agent uses the URI `http://host/icons/abc.gif' to
 access the resource linked from the <IMG> element.
 If the URI in the address of the head anchor is the same as the
 base URI, then the base document is sufficient as a
 representation of the resource. A user agent must _not_, for
 example, use any network information retrieval protocols to
 obtain a new representation of the resourse.
 For example, if the base uri is
 `http:'/www.w3.org/hypertext/WWW/TheProject.html/, then each of
 the following markup constructs indicates a link whose head and
 tail anchors have the same URI in their address:
 <a href="#xyz">
 <a href="../WWW/TheProject.html">
 <a href="./TheProject.html">
 <a href="TheProject.html">
 <a href="TheProject.html#z21">
 <a href="../../hypertext/WWW/TheProject.html">
 <a href="http://www.w3.org/hypertext/WWW/TheProject.html">
7.2. Activation of Hyperlinks
 An HTML user agent allows the user to navigate the content of
 the document and request activation of hyperlinks denoted by <A>
 elements. HTML user agents should also allow activation of
 <LINK> element hyperlinks.
 To activate a link, the user agent obtains a representation of
 the resource identified in the address of the head anchor. If
 the representation is another HTML document, navigation may
 begin again with this new document. The base URI for navigation
 is taken from the head anchor by default; however, any <BASE>
 tag in the destination document overrides this default. The
 process of obtaining the destination document may also override
 the base URI, as in the case of an HTTP `URI:' header or
 redirection transaction.
7.3. Simultaneous Presentation of Image Resources
 An HTML user agent may activate hyperlinks indicated by <IMG>
 and <INPUT> elements concurrently with processing the document;
 that is, image hyperlinks may be processed without explicit
 request by the user. Image resources should be embedded in the
 presentation at the point of the tail anchor, that is the <IMG>
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 or <INPUT> element.
 <LINK> hyperlinks may also be processed without explicit user
 request; for example, style sheet resources may be processed
 before or during the processing of the document.
7.4. Fragment Identifiers
 Any characters following a `#' character in a hypertext address
 constitute a fragment identifier. In particular, an address of
 the form `#fragment' refers to an anchor in the same document.
 The meaning of fragment identifiers depends on the media type of
 the representation of the anchor's resource. For `text/html'
 representations, it refers to the <A> element with a NAME
 attribute whose value is the same as the fragment identifier.
 The matching is case sensitive. The document should have exactly
 one such element. The user agent should indicate the anchor
 element, for example by scrolling to and/or highlighting the
 phrase.
 For example, if the base URI is `http://host/x/y.html' and the
 user activated the link denoted by the following markup:
 <p> See: <a href="app1.html#bananas">appendix 1</a>
 for more detail on bananas.
 Then the user agent accesses the resource identified by
 `http://host/x/app1.html'. Assuming the resource is represented
 using the `text/html' media type, the user agent must locate the
 <A> element whose NAME attribute is `bananas' and begin
 navigation there.
7.5. Queries and Indexes
 The <ISINDEX> element represents a set of hyperlinks. The user
 can choose from the set by providing keywords to the user agent.
 The user agent computes the head URI by appending `?' and the
 keywords to the base URI. The keywords are escaped according to
 [URL] and joined by `+'. For example, if a document contains:
 <BASE HREF="http://host/index">
 <ISINDEX>
 and the user provides the keywords `apple' and `berry', then the
 user agent must access the resource
 `http://host/index?apple+berry'.
 <FORM> elements with `METHOD=GET' also represent sets of
 hyperlinks. See 8.2.2, "Query Forms: METHOD=GET" for details.
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7.6. Image Maps
 If the ISMAP attribute is present on an <IMG> element, the <IMG>
 element must be contained in an <A> element with an HREF
 present. This construct represents a set of hyperlinks. The user
 can choose from the set by choosing a pixel of the image. The
 user agent computes the head URI by appending `?' and the x and
 y coordinates of the pixel to the URI given in the <A> element.
 For example, if a document contains:
 <!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN">
 <head><title>ImageMap Example</title>
 <BASE HREF="http://host/index"></head>
 <body>
 <p> Choose any of these icons:<br>
 <a href="/cgi-bin/imagemap"><img ismap src="icons.gif"></a>
 and the user chooses the upper-leftmost pixel, the chosen
 hyperlink is the one with the URI
 `http://host/cgi-bin/imagemap?0,0'.
8. Forms
 A form is a template for a form data set and an associated
 method and action URI. A form data set is a sequence of
 name/value pair fields. The names are specified on the NAME
 attributes of form input elements, and the values are given
 initial values by various forms of markup and edited by the
 user. The resulting form data set is used to access an
 information service as a function of the action and method.
 Forms elements can be mixed in with document structuring
 elements. For example, a <PRE> element may contain a <FORM>
 element, or a <FORM> element may contain lists which contain
 <INPUT> elements. This gives considerable flexibility in
 designing the layout of forms.
 Form processing is a level 2 feature.
8.1. Form Elements
8.1.1. Form: FORM
 The <FORM> element contains a sequence of input elements, along
 with document structuring elements. The attributes are:
 ACTION
 specifies the action URI for the form. The action URI of
 a form defaults to the base URI of the document (see 7,
 "Hyperlinks").
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 METHOD
 selects a method of accessing the action URI. The set of
 applicable methods is a function of the scheme of the
 action URI of the form. See 8.2.2, "Query Forms:
 METHOD=GET" and 8.2.3, "Forms with Side-Effects:
 METHOD=POST".
 ENCTYPE
 specifies the media type used to encode the name/value
 pairs for transport, in case the protocol does not
 itself impose a format. See 8.2.1, "The form-urlencoded
 Media Type".
8.1.2. Input Field: INPUT
 The <INPUT> element represents a field for user input. The TYPE
 attribute discriminates between several variations of fields.
 The <INPUT> element has a number of attributes. The set of
 applicable attributes depends on the value of the TYPE
 attribute.
8.1.2.1. Text Field: INPUT TYPE=TEXT
 The default vaule of the TYPE attribute is `TEXT', indicating a
 single line text entry fields. (Use the <TEXTAREA> element for
 multi-line text fields.)
 Required attributes are:
 NAME
 name for the form field corresponding to this element.
 The optional attriubtes are:
 MAXLENGTH
 constrains the number of characters that can be entered
 into a text input field. If the value of MAXLENGTH is
 greater the the value of the SIZE attribute, the field
 should scroll appropriately. The default number of
 characters is unlimited.
 SIZE
 specifies the amount of display space allocated to this
 input field according to its type. The default depends
 on the user agent.
 VALUE
 The initial value of the field.
 For example:
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 <p>Street Address: <input name=street><br>
 Postal City code: <input name=city size=16 maxlength=16><br>
 Zip Code: <input name=zip size=10 maxlength=10 value="99999-9999"><br>
8.1.2.2. Password Field: INPUT TYPE=PASSWORD
 An <INPUT> element with `TYPE=PASSWORD' is a text field as
 above, except that the value is obscured as it is entered. (see
 also: 10, "Security Considerations").
 For example:
 <p>Name: <input name=login> Password: <input type=password name=passwd>
8.1.2.3. Check Box: INPUT TYPE=CHECKBOX
 An <INPUT> element with `TYPE=CHECKBOX' represents a boolean
 choice. A set of such elements with the same name represents an
 n-of-many choice field. Required attributes are:
 NAME
 symbolic name for the form field corresponding to this
 element or group of elements.
 VALUE
 The portion of the value of the field contributed by
 this element.
 Optional attributes are:
 CHECKED
 indicates that the initial state is on.
 For example:
 <p>What flavors do you like?
 <input type=checkbox name=flavor value=vanilla>Vanilla<br>
 <input type=checkbox name=flavor value=strawberry>Strawberry<br>
 <input type=checkbox name=flavor value=chocolate checked>Chocolate<br>
8.1.2.4. Radio Button: INPUT TYPE=RADIO
 An <INPUT> element with `TYPE=RADIO' represents a boolean
 choice. A set of such elements with the same name represents a
 1-of-many choice field. The NAME and VALUE attributes are
 required as for check boxes. Optional attributes are:
 CHECKED
 indicates that the initial state is on.
 At all times, exactly one of the radio buttons in a set is
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 checked. If none of the <INPUT> elements of a set of radio
 buttons specifies `CHECKED', then the user agent must check the
 first radio button of the set initially.
 For example:
 <p>Which is your favorite?
 <input type=radio name=flavor value=vanilla>Vanilla<br>
 <input type=radio name=flavor value=strawberry>Strawberry<br>
 <input type=radio name=flavor value=chocolate>Chocolate<br>
8.1.2.5. Image Pixel: INPUT TYPE=IMAGE
 An <INPUT> element with `TYPE=IMAGE' specifies an image resource
 to display, and allows input of two form fields: the x and y
 coordinate of a pixel chosen from the image. The names of the
 fields are the name of the field with `.x' and `.y' appended.
 `TYPE=IMAGE' implies `TYPE=SUBMIT' processing; that is, when a
 pixel is chosen, the form as a whole is submitted.
 The NAME attribute is required as for other input fields. The
 SRC attribute is required and the ALIGN is optional as for the
 <IMG> element (see 5.10, "Image: IMG").
 For example:
 <p>Choose a point on the map:
 <input type=image name=point src="map.gif">
8.1.2.6. Hidden Field: INPUT TYPE=HIDDEN
 An <INPUT> element with `TYPE=HIDDEN' represents a hidden
 field.The user does not interact with this field; instead, the
 VALUE attribute specifies the value of the field. The NAME and
 VALUE attributes are required.
 For example:
 <input type=hidden name=context value="l2k3j4l2k3j4l2k3j4lk23">
8.1.2.7. Submit Button: INPUT TYPE=SUBMIT
 An <INPUT> element with `TYPE=SUBMIT' represents an input
 option, typically a button, that instructs the user agent to
 submit the form. Optional attributes are:
 NAME
 indicates that this element contributes a form field
 whose value is given by the VALUE attribute. If the NAME
 attribute is not present, this element does not
 contribute a form field.
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 VALUE
 indicates a label for the input (button).
 You may submit this request internally:
 <input type=submit name=recipient value=internal><br>
 or to the external world:
 <input type=submit name=recipient value=world>
8.1.2.8. Reset Button: INPUT TYPE=RESET
 An <INPUT> element with `TYPE=RESET' represents an input option,
 typically a button, that instructs the user agent to reset the
 form's fields to their initial states. The VALUE attribute, if
 present, indicates a label for the input (button).
 When you are finished, you may submit this request:
 <input type=submit><br>
 You may clear the form and start over at any time: <input type=reset>
8.1.3. Selection: SELECT
 The <SELECT> element constrains the form field to an enumerated
 list of values. The values are given in <OPTION> elements.
 Attributes are:
 MULTIPLE
 indicates that more than one option may be included in
 the value.
 NAME
 specifies the name of the form field.
 SIZE
 specifies the number of visible items. Select fields of
 size one are typically pop-down menus, whereas select
 fields with size greater than one are typically lists.
 For example:
 <SELECT NAME="flavor">
 <OPTION>Vanilla
 <OPTION>Strawberry
 <OPTION value="RumRasin">Rum and Raisin
 <OPTION selected>Peach and Orange
 </SELECT>
 The initial state has the first option selected, unless a
 SELECTED attribute is present on any of the <OPTION> elements.
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8.1.3.1. Option: OPTION
 The Option element can only occur within a Select element. It
 represents one choice, and has the following attributes:
 SELECTED
 Indicates that this option is initially selected.
 VALUE
 indicates the value to be returned if this option is
 chosen. The field value defaults to the content of the
 <OPTION> element.
 The content of the <OPTION> element is presented to the user to
 represent the option. It is used as a returned value if the
 VALUE attribute is not present.
8.1.4. Text Area: TEXTAREA
 The <TEXTAREA> element represents a multi-line text field.
 Attributes are:
 COLS
 the number of visible columns to display for the text
 area, in characters.
 NAME
 Specifies the name of the form field.
 ROWS
 The number of visible rows to display for the text area,
 in characters.
 For example:
 <TEXTAREA NAME="address" ROWS=6 COLS=64>
 HaL Computer Systems
 1315 Dell Avenue
 Campbell, California 95008
 </TEXTAREA>
 The content of the <TEXTAREA> element is the field's initial
 value.
 Typically, the ROWS and COLS attributes determine the visible
 dimension of the field in characters. The field is typically
 rendered in a fixed-width font. HTML user agents should allow
 text to extend beyond these limits by scrolling as needed.
8.2. Form Submission
 An HTML user agent begins processing a form by presenting the
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 document with the fields in their initial state. The user is
 allowed to modify the fields, constrained by the field type etc.
 When the user indicates that the form should be submitted (using
 a submit button or image input), the form data set is processed
 according to its method, action URI and enctype.
 When there is only one single-line text input field in a form,
 the user agent should accept Enter in that field as a request to
 submit the form.
8.2.1. The form-urlencoded Media Type
 The default encoding for all forms is
 `application/x-www-form-urlencoded'. A form data set is
 represented in this media type as follows:
 1. The form field names and values are escaped: space
 characters are replaced by `+', and then reserved characters
 are escaped as per [URL]; that is, non-alphanumeric
 characters are replaced by `%HH', a percent sign and two
 hexadecimal digits representing the ASCII code of the
 character. Line breaks, as in multi-line text field values,
 are represented as CR LF pairs, i.e. `%0D%0A'.
 2. The fields are listed in the order they appear in the
 document with the name separated from the value by `=' and
 the pairs separated from each other by `&'. Fields with null
 values may be omitted. In particular, unselected radio
 buttons and checkboxes should not appear in the encoded
 data, but hidden fields with VALUE attributes present
 should.
 NOTE - The URI from a query form submission can be
 used in a normal anchor style hyperlink.
 Unfortunately, the use of the `&' character to
 separate form fields interacts with its use in SGML
 attribute values as an entity reference delimiter.
 For example, the URI `http://host/?x=1&y=2' must be
 written `<a href="http://host/?x=1&#38;y=2"' or `<a
 href="http://host/?x=1&amp;y=2">'.
 HTTP server implementors, and in particular, CGI
 implementors are encouraged to support the use of
 `;' in place of `&' to save users the trouble of
 escaping `&' characters this way.
8.2.2. Query Forms: METHOD=GET
 If the processing of a form is idempotent (i.e. it has no
 lasting observable effect on the state of the world), then the
 form method should be `GET'. Many database searches have no
 visible side-effects and make ideal applications of query forms.
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 To process a form whose action URL is an HTTP URL and whose
 method is `GET', the user agent starts with the action URI and
 appends a `?' and the form data set, in
 `application/x-www-form-urlencoded' format as above. The user
 agent then traverses the link to this URI just as if it were an
 anchor (see 7.2, "Activation of Hyperlinks").
 NOTE - The URL encoding may result in very long URIs,
 which cause some historical HTTP server implementations
 to exhibit defective behavior. As a result, some HTML
 forms are written using `METHOD=POST' even though the
 form submission has no side-effects.
8.2.3. Forms with Side-Effects: METHOD=POST
 If the service associated with the processing of a form has side
 effects (for example, modification of a database or subscription
 to a service), the method should be `POST'.
 To process a form whose action URL is an HTTP URL and whose
 method is `POST', the user agent conducts an HTTP POST
 transaction using the action URI, and a message body of type
 `application/x-www-form-urlencoded' format as above. The user
 agent should display the response from the HTTP POST interaction
 just as it would display the response from an HTTP GET above.
8.2.4. Example Form Submission: Questionnaire Form
 Consider the following document:
 <!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN">
 <title>Sample of HTML Form Submission</title>
 <H1>Sample Questionnaire</H1>
 <P>Please fill out this questionnaire:
 <FORM METHOD="POST" ACTION="http://www.w3.org/sample">
 <P>Your name: <INPUT NAME="name" size="48">
 <P>Male <INPUT NAME="gender" TYPE=RADIO VALUE="male">
 <P>Female <INPUT NAME="gender" TYPE=RADIO VALUE="female">
 <P>Number in family: <INPUT NAME="family" TYPE=text>
 <P>Cities in which you maintain a residence:
 <UL>
 <LI>Kent <INPUT NAME="city" TYPE=checkbox VALUE="kent">
 <LI>Miami <INPUT NAME="city" TYPE=checkbox VALUE="miami">
 <LI>Other <TEXTAREA NAME="other" cols=48 rows=4></textarea>
 </UL>
 Nickname: <INPUT NAME="nickname" SIZE="42">
 <P>Thank you for responding to this questionnaire.
 <P><INPUT TYPE=SUBMIT> <INPUT TYPE=RESET>
 </FORM>
 The initial state of the form data set is:
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 name
 ``''
 gender
 ``male''
 family
 ``''
 other
 ``''
 nickname
 ``''
 Note that the radio input has an initial value, while the
 checkbox has none.
 The user might edit the fields and request that the form be
 submitted. At that point, suppose the values are:
 name
 ``John Doe''
 gender
 ``male''
 family
 ``5''
 city
 ``kent''
 city
 ``miami''
 other
 ``abc\ndef''
 nickname
 ``J&D''
 The user agent then conducts an HTTP POST transaction using the
 URI `http://www.w3.org/sample'. The message body would be
 (ignore the line break):
 name=John+Doe&gender=male&family=5&city=kent&city=miami&
 other=abc%0D%0Adef&nickname=J%26D
9. HTML Public Text
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9.1. HTML DTD
 This is the Document Type Definition for the HyperText Markup
 Language, level 2.
<!-- html.dtd
 Document Type Definition for the HyperText Markup Language
 (HTML DTD)
 $Id: html.dtd,v 1.29 1995年08月04日 17:50:22 connolly Exp $
 Author: Daniel W. Connolly <connolly@w3.org>
 See Also: html.decl, html-1.dtd
 http://www.w3.org/hypertext/WWW/MarkUp/MarkUp.html
- -->
<!ENTITY % HTML.Version
 "-//IETF//DTD HTML 2.0//EN"
 -- Typical usage:
 <!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML//EN">
 <html>
 ...
 </html>
 --
 >
<!--============ Feature Test Entities ========================-->
<!ENTITY % HTML.Recommended "IGNORE"
 -- Certain features of the language are necessary for
 compatibility with widespread usage, but they may
 compromise the structural integrity of a document.
 This feature test entity enables a more prescriptive
 document type definition that eliminates
 those features.
 -->
<![ %HTML.Recommended [
 <!ENTITY % HTML.Deprecated "IGNORE">
]]>
<!ENTITY % HTML.Deprecated "INCLUDE"
 -- Certain features of the language are necessary for
 compatibility with earlier versions of the specification,
 but they tend to be used an implemented inconsistently,
 and their use is deprecated. This feature test entity
 enables a document type definition that eliminates
 these features.
 -->
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<!ENTITY % HTML.Highlighting "INCLUDE"
 -- Use this feature test entity to validate that a
 document uses no highlighting tags, which may be
 ignored on minimal implementations.
 -->
<!ENTITY % HTML.Forms "INCLUDE"
 -- Use this feature test entity to validate that a document
 contains no forms, which may not be supported in minimal
 implementations
 -->
<!--============== Imported Names ==============================-->
<!ENTITY % Content-Type "CDATA"
 -- meaning an internet media type
 (aka MIME content type, as per RFC1521)
 -->
<!ENTITY % HTTP-Method "GET | POST"
 -- as per HTTP specification, in progress
 -->
<!--========= DTD "Macros" =====================-->
<!ENTITY % heading "H1|H2|H3|H4|H5|H6">
<!ENTITY % list " UL | OL | DIR | MENU " >
<!--======= Character mnemonic entities =================-->
<!ENTITY % ISOlat1 PUBLIC
 "ISO 8879-1986//ENTITIES Added Latin 1//EN//HTML">
%ISOlat1;
<!ENTITY amp CDATA "&#38;" -- ampersand -->
<!ENTITY gt CDATA "&#62;" -- greater than -->
<!ENTITY lt CDATA "&#60;" -- less than -->
<!ENTITY quot CDATA "&#34;" -- double quote -->
<!--========= SGML Document Access (SDA) Parameter Entities =====-->
<!-- HTML 2.0 contains SGML Document Access (SDA) fixed attributes
in support of easy transformation to the International Committee
for Accessible Document Design (ICADD) DTD
 "-//EC-USA-CDA/ICADD//DTD ICADD22//EN".
ICADD applications are designed to support usable access to
structured information by print-impaired individuals through
Braille, large print and voice synthesis. For more information on
SDA & ICADD: 
 - ISO 12083:1993, Annex A.8, Facilities for Braille,
 large print and computer voice
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 - ICADD ListServ
 <ICADD%ASUACAD.BITNET@ARIZVM1.ccit.arizona.edu>
 - Usenet news group bit.listserv.easi
 - Recording for the Blind, +1 800 221 4792
- -->
<!ENTITY % SDAFORM "SDAFORM CDATA #FIXED"
 -- one to one mapping -->
<!ENTITY % SDARULE "SDARULE CDATA #FIXED"
 -- context-sensitive mapping -->
<!ENTITY % SDAPREF "SDAPREF CDATA #FIXED"
 -- generated text prefix -->
<!ENTITY % SDASUFF "SDASUFF CDATA #FIXED"
 -- generated text suffix -->
<!ENTITY % SDASUSP "SDASUSP NAME #FIXED"
 -- suspend transform process -->
<!--========== Text Markup =====================-->
<![ %HTML.Highlighting [
<!ENTITY % font " TT | B | I ">
<!ENTITY % phrase "EM | STRONG | CODE | SAMP | KBD | VAR | CITE ">
<!ENTITY % text "#PCDATA | A | IMG | BR | %phrase | %font">
<!ELEMENT (%font;|%phrase) - - (%text)*>
<!ATTLIST ( TT | CODE | SAMP | KBD | VAR )
 %SDAFORM; "Lit"
 >
<!ATTLIST ( B | STRONG )
 %SDAFORM; "B"
 >
<!ATTLIST ( I | EM | CITE )
 %SDAFORM; "It"
 >
<!-- <TT> Typewriter text -->
<!-- <B> Bold text -->
<!-- <I> Italic text -->
<!-- <EM> Emphasized phrase -->
<!-- <STRONG> Strong emphais -->
<!-- <CODE> Source code phrase -->
<!-- <SAMP> Sample text or characters -->
<!-- <KBD> Keyboard phrase, e.g. user input -->
<!-- <VAR> Variable phrase or substituable -->
<!-- <CITE> Name or title of cited work -->
<!ENTITY % pre.content "#PCDATA | A | HR | BR | %font | %phrase">
]]>
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<!ENTITY % text "#PCDATA | A | IMG | BR">
<!ELEMENT BR - O EMPTY>
<!ATTLIST BR
 %SDAPREF; "&#RE;"
 >
<!-- <BR> Line break -->
<!--========= Link Markup ======================-->
<!ENTITY % linkType "NAMES">
<!ENTITY % linkExtraAttributes
 "REL %linkType #IMPLIED
 REV %linkType #IMPLIED
 URN CDATA #IMPLIED
 TITLE CDATA #IMPLIED
 METHODS NAMES #IMPLIED
 ">
<![ %HTML.Recommended [
 <!ENTITY % A.content "(%text)*"
 -- <H1><a name="xxx">Heading</a></H1>
 is preferred to
 <a name="xxx"><H1>Heading</H1></a>
 -->
]]>
<!ENTITY % A.content "(%heading|%text)*">
<!ELEMENT A - - %A.content -(A)>
<!ATTLIST A
 HREF CDATA #IMPLIED
 NAME CDATA #IMPLIED
 %linkExtraAttributes;
 %SDAPREF; "<Anchor: #AttList>"
 >
<!-- <A> Anchor; source/destination of link -->
<!-- <A NAME="..."> Name of this anchor -->
<!-- <A HREF="..."> Address of link destination -->
<!-- <A URN="..."> Permanent address of destination -->
<!-- <A REL=...> Relationship to destination -->
<!-- <A REV=...> Relationship of destination to this -->
<!-- <A TITLE="..."> Title of destination (advisory) -->
<!-- <A METHODS="..."> Operations on destination (advisory) -->
<!--========== Images ==========================-->
<!ELEMENT IMG - O EMPTY>
<!ATTLIST IMG
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 SRC CDATA #REQUIRED
 ALT CDATA #IMPLIED
 ALIGN (top|middle|bottom) #IMPLIED
 ISMAP (ISMAP) #IMPLIED
 %SDAPREF; "<Fig><?SDATrans Img: #AttList>#AttVal(Alt)</Fig>"
 >
<!-- <IMG> Image; icon, glyph or illustration -->
<!-- <IMG SRC="..."> Address of image object -->
<!-- <IMG ALT="..."> Textual alternative -->
<!-- <IMG ALIGN=...> Position relative to text -->
<!-- <IMG ISMAP> Each pixel can be a link -->
<!--========== Paragraphs=======================-->
<!ELEMENT P - O (%text)*>
<!ATTLIST P
 %SDAFORM; "Para"
 >
<!-- <P> Paragraph -->
<!--========== Headings, Titles, Sections ===============-->
<!ELEMENT HR - O EMPTY>
<!ATTLIST HR
 %SDAPREF; "&#RE;&#RE;"
 >
<!-- <HR> Horizontal rule -->
<!ELEMENT ( %heading ) - - (%text;)*>
<!ATTLIST H1
 %SDAFORM; "H1"
 >
<!ATTLIST H2
 %SDAFORM; "H2"
 >
<!ATTLIST H3
 %SDAFORM; "H3"
 >
<!ATTLIST H4
 %SDAFORM; "H4"
 >
<!ATTLIST H5
 %SDAFORM; "H5"
 >
<!ATTLIST H6
 %SDAFORM; "H6"
 >
<!-- <H1> Heading, level 1 -->
<!-- <H2> Heading, level 2 -->
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<!-- <H3> Heading, level 3 -->
<!-- <H4> Heading, level 4 -->
<!-- <H5> Heading, level 5 -->
<!-- <H6> Heading, level 6 -->
<!--========== Text Flows ======================-->
<![ %HTML.Forms [
 <!ENTITY % block.forms "BLOCKQUOTE | FORM | ISINDEX">
]]>
<!ENTITY % block.forms "BLOCKQUOTE">
<![ %HTML.Deprecated [
 <!ENTITY % preformatted "PRE | XMP | LISTING">
]]>
<!ENTITY % preformatted "PRE">
<!ENTITY % block "P | %list | DL
 | %preformatted
 | %block.forms">
<!ENTITY % flow "(%text|%block)*">
<!ENTITY % pre.content "#PCDATA | A | HR | BR">
<!ELEMENT PRE - - (%pre.content)*>
<!ATTLIST PRE
 WIDTH NUMBER #implied
 %SDAFORM; "Lit"
 >
<!-- <PRE> Preformatted text -->
<!-- <PRE WIDTH=...> Maximum characters per line -->
<![ %HTML.Deprecated [
<!ENTITY % literal "CDATA"
 -- historical, non-conforming parsing mode where
 the only markup signal is the end tag
 in full
 -->
<!ELEMENT (XMP|LISTING) - - %literal>
<!ATTLIST XMP
 %SDAFORM; "Lit"
 %SDAPREF; "Example:&#RE;"
 >
<!ATTLIST LISTING
 %SDAFORM; "Lit"
 %SDAPREF; "Listing:&#RE;"
 >
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<!-- <XMP> Example section -->
<!-- <LISTING> Computer listing -->
<!ELEMENT PLAINTEXT - O %literal>
<!-- <PLAINTEXT> Plain text passage -->
<!ATTLIST PLAINTEXT
 %SDAFORM; "Lit"
 >
]]>
<!--========== Lists ==================-->
<!ELEMENT DL - - (DT | DD)+>
<!ATTLIST DL
 COMPACT (COMPACT) #IMPLIED
 %SDAFORM; "List"
 %SDAPREF; "Definition List:"
 >
<!ELEMENT DT - O (%text)*>
<!ATTLIST DT
 %SDAFORM; "Term"
 >
<!ELEMENT DD - O %flow>
<!ATTLIST DD
 %SDAFORM; "LItem"
 >
<!-- <DL> Definition list, or glossary -->
<!-- <DL COMPACT> Compact style list -->
<!-- <DT> Term in definition list -->
<!-- <DD> Definition of term -->
<!ELEMENT (OL|UL) - - (LI)+>
<!ATTLIST OL
 COMPACT (COMPACT) #IMPLIED
 %SDAFORM; "List"
 >
<!ATTLIST UL
 COMPACT (COMPACT) #IMPLIED
 %SDAFORM; "List"
 >
<!-- <UL> Unordered list -->
<!-- <UL COMPACT> Compact list style -->
<!-- <OL> Ordered, or numbered list -->
<!-- <OL COMPACT> Compact list style -->
<!ELEMENT (DIR|MENU) - - (LI)+ -(%block)>
<!ATTLIST DIR
 COMPACT (COMPACT) #IMPLIED
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 %SDAFORM; "List"
 %SDAPREF; "<LHead>Directory</LHead>"
 >
<!ATTLIST MENU
 COMPACT (COMPACT) #IMPLIED
 %SDAFORM; "List"
 %SDAPREF; "<LHead>Menu</LHead>"
 >
<!-- <DIR> Directory list -->
<!-- <DIR COMPACT> Compact list style -->
<!-- <MENU> Menu list -->
<!-- <MENU COMPACT> Compact list style -->
<!ELEMENT LI - O %flow>
<!ATTLIST LI
 %SDAFORM; "LItem"
 >
<!-- <LI> List item -->
<!--========== Document Body ===================-->
<![ %HTML.Recommended [
 <!ENTITY % body.content "(%heading|%block|HR|ADDRESS|IMG)*"
 -- <h1>Heading</h1>
 <p>Text ...
 is preferred to
 <h1>Heading</h1>
 Text ...
 -->
]]>
<!ENTITY % body.content "(%heading | %text | %block |
 HR | ADDRESS)*">
<!ELEMENT BODY O O %body.content>
<!-- <BODY> Document body -->
<!ELEMENT BLOCKQUOTE - - %body.content>
<!ATTLIST BLOCKQUOTE
 %SDAFORM; "BQ"
 >
<!-- <BLOCKQUOTE> Quoted passage -->
<!ELEMENT ADDRESS - - (%text|P)*>
<!ATTLIST ADDRESS
 %SDAFORM; "Lit"
 %SDAPREF; "Address:&#RE;"
 >
<!-- <ADDRESS> Address, signature, or byline -->
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<!--======= Forms ====================-->
<![ %HTML.Forms [
<!ELEMENT FORM - - %body.content -(FORM) +(INPUT|SELECT|TEXTAREA)>
<!ATTLIST FORM
 ACTION CDATA #IMPLIED
 METHOD (%HTTP-Method) GET
 ENCTYPE %Content-Type; "application/x-www-form-urlencoded"
 %SDAPREF; "<Para>Form:</Para>"
 %SDASUFF; "<Para>Form End.</Para>"
 >
<!-- <FORM> Fill-out or data-entry form -->
<!-- <FORM ACTION="..."> Address for completed form -->
<!-- <FORM METHOD=...> Method of submitting form -->
<!-- <FORM ENCTYPE="..."> Representation of form data -->
<!ENTITY % InputType "(TEXT | PASSWORD | CHECKBOX |
 RADIO | SUBMIT | RESET |
 IMAGE | HIDDEN )">
<!ELEMENT INPUT - O EMPTY>
<!ATTLIST INPUT
 TYPE %InputType TEXT
 NAME CDATA #IMPLIED
 VALUE CDATA #IMPLIED
 SRC CDATA #IMPLIED
 CHECKED (CHECKED) #IMPLIED
 SIZE CDATA #IMPLIED
 MAXLENGTH NUMBER #IMPLIED
 ALIGN (top|middle|bottom) #IMPLIED
 %SDAPREF; "Input: "
 >
<!-- <INPUT> Form input datum -->
<!-- <INPUT TYPE=...> Type of input interaction -->
<!-- <INPUT NAME=...> Name of form datum -->
<!-- <INPUT VALUE="..."> Default/initial/selected value -->
<!-- <INPUT SRC="..."> Address of image -->
<!-- <INPUT CHECKED> Initial state is "on" -->
<!-- <INPUT SIZE=...> Field size hint -->
<!-- <INPUT MAXLENGTH=...> Data length maximum -->
<!-- <INPUT ALIGN=...> Image alignment -->
<!ELEMENT SELECT - - (OPTION+) -(INPUT|SELECT|TEXTAREA)>
<!ATTLIST SELECT
 NAME CDATA #REQUIRED
 SIZE NUMBER #IMPLIED
 MULTIPLE (MULTIPLE) #IMPLIED
 %SDAFORM; "List"
 %SDAPREF;
 "<LHead>Select #AttVal(Multiple)</LHead>"
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 >
<!-- <SELECT> Selection of option(s) -->
<!-- <SELECT NAME=...> Name of form datum -->
<!-- <SELECT SIZE=...> Options displayed at a time -->
<!-- <SELECT MULTIPLE> Multiple selections allowed -->
<!ELEMENT OPTION - O (#PCDATA)*>
<!ATTLIST OPTION
 SELECTED (SELECTED) #IMPLIED
 VALUE CDATA #IMPLIED
 %SDAFORM; "LItem"
 %SDAPREF;
 "Option: #AttVal(Value) #AttVal(Selected)"
 >
<!-- <OPTION> A selection option -->
<!-- <OPTION SELECTED> Initial state -->
<!-- <OPTION VALUE="..."> Form datum value for this option-->
<!ELEMENT TEXTAREA - - (#PCDATA)* -(INPUT|SELECT|TEXTAREA)>
<!ATTLIST TEXTAREA
 NAME CDATA #REQUIRED
 ROWS NUMBER #REQUIRED
 COLS NUMBER #REQUIRED
 %SDAFORM; "Para"
 %SDAPREF; "Input Text -- #AttVal(Name): "
 >
<!-- <TEXTAREA> An area for text input -->
<!-- <TEXTAREA NAME=...> Name of form datum -->
<!-- <TEXTAREA ROWS=...> Height of area -->
<!-- <TEXTAREA COLS=...> Width of area -->
]]>
<!--======= Document Head ======================-->
<![ %HTML.Recommended [
 <!ENTITY % head.extra "">
]]>
<!ENTITY % head.extra "& NEXTID?">
<!ENTITY % head.content "TITLE & ISINDEX? & BASE? %head.extra">
<!ELEMENT HEAD O O (%head.content) +(META|LINK)>
<!-- <HEAD> Document head -->
<!ELEMENT TITLE - - (#PCDATA)*>
<!ATTLIST TITLE
 %SDAFORM; "Ti" >
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<!-- <TITLE> Title of document -->
<!ELEMENT LINK - O EMPTY>
<!ATTLIST LINK
 HREF CDATA #REQUIRED
 %linkExtraAttributes;
 %SDAPREF; "Linked to : #AttVal (TITLE) (URN) (HREF)>" >
<!-- <LINK> Link from this document -->
<!-- <LINK HREF="..."> Address of link destination -->
<!-- <LINK URN="..."> Lasting name of destination -->
<!-- <LINK REL=...> Relationship to destination -->
<!-- <LINK REV=...> Relationship of destination to this -->
<!-- <LINK TITLE="..."> Title of destination (advisory) -->
<!-- <LINK METHODS="..."> Operations allowed (advisory) -->
<!ELEMENT ISINDEX - O EMPTY>
<!ATTLIST ISINDEX
 %SDAPREF;
 "<Para>[Document is indexed/searchable.]</Para>">
<!-- <ISINDEX> Document is a searchable index -->
<!ELEMENT BASE - O EMPTY>
<!ATTLIST BASE
 HREF CDATA #REQUIRED >
<!-- <BASE> Base context document -->
<!-- <BASE HREF="..."> Address for this document -->
<!ELEMENT NEXTID - O EMPTY>
<!ATTLIST NEXTID
 N CDATA #REQUIRED >
<!-- <NEXTID> Next ID to use for link name -->
<!-- <NEXTID N=...> Next ID to use for link name -->
<!ELEMENT META - O EMPTY>
<!ATTLIST META
 HTTP-EQUIV NAME #IMPLIED
 NAME NAME #IMPLIED
 CONTENT CDATA #REQUIRED >
<!-- <META> Generic Metainformation -->
<!-- <META HTTP-EQUIV=...> HTTP response header name -->
<!-- <META NAME=...> Metainformation name -->
<!-- <META CONTENT="..."> Associated information -->
<!--======= Document Structure =================-->
<![ %HTML.Deprecated [
 <!ENTITY % html.content "HEAD, BODY, PLAINTEXT?">
]]>
<!ENTITY % html.content "HEAD, BODY">
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<!ELEMENT HTML O O (%html.content)>
<!ENTITY % version.attr "VERSION CDATA #FIXED '%HTML.Version;'">
<!ATTLIST HTML
 %version.attr;
 %SDAFORM; "Book"
 >
<!-- <HTML> HTML Document -->
9.2. Strict HTML DTD
 This document type declaration refers to the HTML DTD with the
 `HTML.Recommended' entity defined as `INCLUDE' rather than
 IGNORE; that is, it refers to the more structurally rigid
 definition of HTML.
<!-- html-s.dtd
 Document Type Definition for the HyperText Markup Language
 with strict validation (HTML Strict DTD).
 $Id: html-s.dtd,v 1.3 1995年06月02日 18:55:46 connolly Exp $
 Author: Daniel W. Connolly <connolly@w3.org>
 See Also: http://www.w3.org/hypertext/WWW/MarkUp/MarkUp.html
- -->
<!ENTITY % HTML.Version
 "-//IETF//DTD HTML 2.0 Strict//EN"
 -- Typical usage:
 <!DOCTYPE HTML PUBLIC
 "-//IETF//DTD HTML Strict//EN">
 <html>
 ...
 </html>
 --
 >
<!-- Feature Test Entities -->
<!ENTITY % HTML.Recommended "INCLUDE">
<!ENTITY % html PUBLIC "-//IETF//DTD HTML 2.0//EN">
%html;
9.3. Level 1 HTML DTD
 This document type declaration refers to the HTML DTD with the
 `HTML.Forms' entity defined as `IGNORE' rather than `INCLUDE'.
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 Documents which contain <FORM> elements do not conform to this
 DTD, and must use the level 2 DTD.
<!-- html-1.dtd
 Document Type Definition for the HyperText Markup Language
 with Level 1 Extensions (HTML Level 1 DTD).
 $Id: html-1.dtd,v 1.2 1995年03月29日 18:53:10 connolly Exp $
 Author: Daniel W. Connolly <connolly@w3.org>
 See Also: http://info.cern.ch/hypertext/WWW/MarkUp/MarkUp.html
- -->
<!ENTITY % HTML.Version
 "-//IETF//DTD HTML 2.0 Level 1//EN"
 -- Typical usage:
 <!DOCTYPE HTML PUBLIC
 "-//IETF//DTD HTML Level 1//EN">
 <html>
 ...
 </html>
 --
 >
<!-- Feature Test Entities -->
<!ENTITY % HTML.Forms "IGNORE">
<!ENTITY % html PUBLIC "-//IETF//DTD HTML 2.0//EN">
%html;
9.4. Strict Level 1 HTML DTD
 This document type declaration refers to the level 1 HTML DTD
 with the `HTML.Recommended' entity defined as `INCLUDE' rather
 than IGNORE; that is, it refers to the more structurally rigid
 definition of HTML.
<!-- html-1s.dtd
 Document Type Definition for the HyperText Markup Language
 Struct Level 1
 $Id: html-1s.dtd,v 1.3 1995年06月02日 18:55:43 connolly Exp $
 Author: Daniel W. Connolly <connolly@w3.org>
 See Also: http://www.w3.org/hypertext/WWW/MarkUp/MarkUp.html
- -->
<!ENTITY % HTML.Version
 "-//IETF//DTD HTML 2.0 Strict Level 1//EN"
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 -- Typical usage:
 <!DOCTYPE HTML PUBLIC
 "-//IETF//DTD HTML Strict Level 1//EN">
 <html>
 ...
 </html>
 --
 >
<!-- Feature Test Entities -->
<!ENTITY % HTML.Recommended "INCLUDE">
<!ENTITY % html-1 PUBLIC "-//IETF//DTD HTML 2.0 Level 1//EN">
%html-1;
9.5. SGML Declaration for HTML
 This is the SGML Declaration for HyperText Markup Language.
<!SGML "ISO 8879:1986"
- --
 SGML Declaration for HyperText Markup Language (HTML).
- --
CHARSET
 BASESET "ISO 646:1983//CHARSET
 International Reference Version
 (IRV)//ESC 2/5 4/0"
 DESCSET 0 9 UNUSED
 9 2 9
 11 2 UNUSED
 13 1 13
 14 18 UNUSED
 32 95 32
 127 1 UNUSED
 BASESET "ISO Registration Number 100//CHARSET
 ECMA-94 Right Part of
 Latin Alphabet Nr. 1//ESC 2/13 4/1"
 DESCSET 128 32 UNUSED
 160 96 32
CAPACITY SGMLREF
 TOTALCAP 150000
 GRPCAP 150000
 ENTCAP 150000
 
SCOPE DOCUMENT
SYNTAX 
 SHUNCHAR CONTROLS 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
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 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 127
 BASESET "ISO 646:1983//CHARSET
 International Reference Version
 (IRV)//ESC 2/5 4/0"
 DESCSET 0 128 0
 FUNCTION
 RE 13
 RS 10
 SPACE 32
 TAB SEPCHAR 9
 
 NAMING LCNMSTRT ""
 UCNMSTRT ""
 LCNMCHAR ".-"
 UCNMCHAR ".-"
 NAMECASE GENERAL YES
 ENTITY NO
 DELIM GENERAL SGMLREF
 SHORTREF SGMLREF
 NAMES SGMLREF
 QUANTITY SGMLREF
 ATTSPLEN 2100
 LITLEN 1024
 NAMELEN 72 -- somewhat arbitrary; taken from
 internet line length conventions --
 PILEN 1024
 TAGLVL 100
 TAGLEN 2100
 GRPGTCNT 150
 GRPCNT 64 
FEATURES
 MINIMIZE
 DATATAG NO
 OMITTAG YES
 RANK NO
 SHORTTAG YES
 LINK
 SIMPLE NO
 IMPLICIT NO
 EXPLICIT NO
 OTHER
 CONCUR NO
 SUBDOC NO
 FORMAL YES
 APPINFO "SDA" -- conforming SGML Document Access application
 --
>
<!-- 
 $Id: html.decl,v 1.17 1995年06月08日 14:59:32 connolly Exp $
 Author: Daniel W. Connolly <connolly@w3.org>
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 See also: http://www.w3.org/hypertext/WWW/MarkUp/MarkUp.html
 -->
9.6. 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 identifier. For example, the
 following are possible catalog entries:
 -- catalog: SGML Open style entity catalog for HTML --
 -- $Id: catalog,v 1.2 1994年11月30日 23:45:18 connolly Exp $ --
 -- Ways to refer to Level 2: most general to most specific --
PUBLIC "-//IETF//DTD HTML//EN" html.dtd
PUBLIC "-//IETF//DTD HTML 2.0//EN" html.dtd
PUBLIC "-//IETF//DTD HTML Level 2//EN" html.dtd
PUBLIC "-//IETF//DTD HTML 2.0 Level 2//EN" html.dtd
 -- Ways to refer to Level 1: most general to most specific --
PUBLIC "-//IETF//DTD HTML Level 1//EN" html-1.dtd
PUBLIC "-//IETF//DTD HTML 2.0 Level 1//EN" html-1.dtd
 -- Ways to refer to Level 0: most general to most specific --
PUBLIC "-//IETF//DTD HTML Level 0//EN" html-0.dtd
PUBLIC "-//IETF//DTD HTML 2.0 Level 0//EN" html-0.dtd
 -- Ways to refer to Strict Level 2: most general to most specif\
c --
PUBLIC "-//IETF//DTD HTML Strict//EN" html-s.dtd
PUBLIC "-//IETF//DTD HTML 2.0 Strict//EN" html-s.dtd
PUBLIC "-//IETF//DTD HTML Strict Level 2//EN" html-s.dtd
PUBLIC "-//IETF//DTD HTML 2.0 Strict Level 2//EN" html-s.dtd
 -- Ways to refer to Strict Level 1: most general to most specif\
c --
PUBLIC "-//IETF//DTD HTML Strict Level 1//EN" html-1s.dtd
PUBLIC "-//IETF//DTD HTML 2.0 Strict Level 1//EN" html-1s.dtd
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 -- Ways to refer to Strict Level 0: most general to most specif\
c --
PUBLIC "-//IETF//DTD HTML Strict Level 0//EN" html-0s.dtd
PUBLIC "-//IETF//DTD HTML 2.0 Strict Level 0//EN" html-0s.dtd
 -- ISO latin 1 entity set for HTML -- 
PUBLIC "ISO 8879-1986//ENTITIES Added Latin 1//EN//HTML" ISOlat1\
sgml
9.7. 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.
9.7.1. Numeric and Special Graphic Entity Set
 The following table lists each of the characters included from
 the Numeric and Special Graphic entity set, along with its name,
 syntax for use, and description. This list is derived from `ISO
 Standard 8879:1986//ENTITIES Numeric and Special Graphic//EN'.
 However, HTML does not include for the entire entity set -- only
 the entities listed below are included.
 GLYPH NAME SYNTAX DESCRIPTION
 < lt &lt; Less than sign
 > gt &gt; Greater than sign
 & amp &amp; Ampersand
 " quot &quot; Double quote sign
9.7.2. ISO Latin 1 Character Entity Set
 The following public text lists each of the characters specified
 in the Added Latin 1 entity set, along with its name, syntax for
 use, and description. This list is derived from ISO Standard
 8879:1986//ENTITIES Added Latin 1//EN. HTML includes the entire
 entity set.
<!-- (C) International Organization for Standardization 1986
 Permission to copy in any form is granted for use with
 conforming SGML systems and applications as defined in
 ISO 8879, provided this notice is included in all copies.
- -->
<!-- Character entity set. Typical invocation:
 <!ENTITY % ISOlat1 PUBLIC
 "ISO 8879-1986//ENTITIES Added Latin 1//EN//HTML">
 %ISOlat1;
- -->
<!-- Modified for use in HTML
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 $Id: ISOlat1.sgml,v 1.2 1994年11月30日 23:45:12 connolly Exp $ -->
<!ENTITY AElig CDATA "&#198;" -- capital AE diphthong (ligature) -->
<!ENTITY Aacute CDATA "&#193;" -- capital A, acute accent -->
<!ENTITY Acirc CDATA "&#194;" -- capital A, circumflex accent -->
<!ENTITY Agrave CDATA "&#192;" -- capital A, grave accent -->
<!ENTITY Aring CDATA "&#197;" -- capital A, ring -->
<!ENTITY Atilde CDATA "&#195;" -- capital A, tilde -->
<!ENTITY Auml CDATA "&#196;" -- capital A, dieresis or umlaut mark -->
<!ENTITY Ccedil CDATA "&#199;" -- capital C, cedilla -->
<!ENTITY ETH CDATA "&#208;" -- capital Eth, Icelandic -->
<!ENTITY Eacute CDATA "&#201;" -- capital E, acute accent -->
<!ENTITY Ecirc CDATA "&#202;" -- capital E, circumflex accent -->
<!ENTITY Egrave CDATA "&#200;" -- capital E, grave accent -->
<!ENTITY Euml CDATA "&#203;" -- capital E, dieresis or umlaut mark -->
<!ENTITY Iacute CDATA "&#205;" -- capital I, acute accent -->
<!ENTITY Icirc CDATA "&#206;" -- capital I, circumflex accent -->
<!ENTITY Igrave CDATA "&#204;" -- capital I, grave accent -->
<!ENTITY Iuml CDATA "&#207;" -- capital I, dieresis or umlaut mark -->
<!ENTITY Ntilde CDATA "&#209;" -- capital N, tilde -->
<!ENTITY Oacute CDATA "&#211;" -- capital O, acute accent -->
<!ENTITY Ocirc CDATA "&#212;" -- capital O, circumflex accent -->
<!ENTITY Ograve CDATA "&#210;" -- capital O, grave accent -->
<!ENTITY Oslash CDATA "&#216;" -- capital O, slash -->
<!ENTITY Otilde CDATA "&#213;" -- capital O, tilde -->
<!ENTITY Ouml CDATA "&#214;" -- capital O, dieresis or umlaut mark -->
<!ENTITY THORN CDATA "&#222;" -- capital THORN, Icelandic -->
<!ENTITY Uacute CDATA "&#218;" -- capital U, acute accent -->
<!ENTITY Ucirc CDATA "&#219;" -- capital U, circumflex accent -->
<!ENTITY Ugrave CDATA "&#217;" -- capital U, grave accent -->
<!ENTITY Uuml CDATA "&#220;" -- capital U, dieresis or umlaut mark -->
<!ENTITY Yacute CDATA "&#221;" -- capital Y, acute accent -->
<!ENTITY aacute CDATA "&#225;" -- small a, acute accent -->
<!ENTITY acirc CDATA "&#226;" -- small a, circumflex accent -->
<!ENTITY aelig CDATA "&#230;" -- small ae diphthong (ligature) -->
<!ENTITY agrave CDATA "&#224;" -- small a, grave accent -->
<!ENTITY aring CDATA "&#229;" -- small a, ring -->
<!ENTITY atilde CDATA "&#227;" -- small a, tilde -->
<!ENTITY auml CDATA "&#228;" -- small a, dieresis or umlaut mark -->
<!ENTITY ccedil CDATA "&#231;" -- small c, cedilla -->
<!ENTITY eacute CDATA "&#233;" -- small e, acute accent -->
<!ENTITY ecirc CDATA "&#234;" -- small e, circumflex accent -->
<!ENTITY egrave CDATA "&#232;" -- small e, grave accent -->
<!ENTITY eth CDATA "&#240;" -- small eth, Icelandic -->
<!ENTITY euml CDATA "&#235;" -- small e, dieresis or umlaut mark -->
<!ENTITY iacute CDATA "&#237;" -- small i, acute accent -->
<!ENTITY icirc CDATA "&#238;" -- small i, circumflex accent -->
<!ENTITY igrave CDATA "&#236;" -- small i, grave accent -->
<!ENTITY iuml CDATA "&#239;" -- small i, dieresis or umlaut mark -->
<!ENTITY ntilde CDATA "&#241;" -- small n, tilde -->
<!ENTITY oacute CDATA "&#243;" -- small o, acute accent -->
<!ENTITY ocirc CDATA "&#244;" -- small o, circumflex accent -->
<!ENTITY ograve CDATA "&#242;" -- small o, grave accent -->
<!ENTITY oslash CDATA "&#248;" -- small o, slash -->
<!ENTITY otilde CDATA "&#245;" -- small o, tilde -->
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<!ENTITY ouml CDATA "&#246;" -- small o, dieresis or umlaut mark -->
<!ENTITY szlig CDATA "&#223;" -- small sharp s, German (sz ligature) -\
>
<!ENTITY thorn CDATA "&#254;" -- small thorn, Icelandic -->
<!ENTITY uacute CDATA "&#250;" -- small u, acute accent -->
<!ENTITY ucirc CDATA "&#251;" -- small u, circumflex accent -->
<!ENTITY ugrave CDATA "&#249;" -- small u, grave accent -->
<!ENTITY uuml CDATA "&#252;" -- small u, dieresis or umlaut mark -->
<!ENTITY yacute CDATA "&#253;" -- small y, acute accent -->
<!ENTITY yuml CDATA "&#255;" -- small y, dieresis or umlaut mark -->
10. 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 [URL] apply.
 The widely deployed methods for submitting forms requests --
 HTTP and SMTP -- provide little assurance of confidentiality.
 Information providers who request sensitive information via
 forms -- especially by way of the `PASSWORD' type input field
 (see 8.1.2, "Input Field: INPUT") -- should be aware and make
 their users aware of the lack of confidentiality.
11. References
 [URI]
 T. Berners-Lee. ``Universal Resource Identifiers in WWW:
 A Unifying Syntax for the Expression of Names and
 Addresses of Objects on the Network as used in the
 World- Wide Web.'' RFC 1630, CERN, June 1994.
 <URL:ftp://ds.internic.net/rfc/rfc1630.txt>
 [URL]
 T. Berners-Lee, L. Masinter, and M. McCahill. ``Uniform
 Resource Locators (URL).'' RFC 1738, CERN, Xerox PARC,
 University of Minnesota, October 1994.
 <URL:ftp://ds.internic.net/rfc/rfc1738.txt>
 [HTTP]
 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.
 <URL:ftp://ds.internic.net/internet-drafts/draft-ietf-http-v10-spec-00.ps>
 [MIME]
 N. Borenstein and N. Freed. ``MIME (Multipurpose
 Internet Mail Extensions) Part One: Mechanisms for
 Specifying and Describing the Format of Internet Message
 Bodies.'' RFC 1521, Bellcore, Innosoft, September 1993.
 <URL:ftp://ds.internic.net/rfc/rfc1521.txt>
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 [RELURL]
 R. Fielding. ``Relative Uniform Resource Locators.'' RFC
 1808, June 1995
 <URL:ftp://ds.internic.net/rfc/rfc1808.txt>
 [GOLD90]
 C. F. Goldfarb. ``The SGML Handbook.'' Y. Rubinsky, Ed.,
 Oxford University Press, 1990. <URL:>
 [DEXTER]
 Frank Halasz and Mayer Schwartz, ``The Dexter Hypertext
 Reference Model'', ``Communications of the ACM'', pp.
 30-39, vol. 37 no. 2, Feb 1994, <URL:>
 [IMEDIA]
 J. Postel. ``Media Type Registration Procedure.'',
 USC/ISI, March 1994.
 <URL:ftp://ds.internic.net/rfc/rfc1590.txt>
 [IANA]
 J. Reynolds and J. Postel. ``Assigned Numbers.'' STD 2,
 RFC 1700, USC/ISI, October 1994.
 <URL:ftp://ds.internic.net/rfc/rfc1700.txt>
 [SQ91]
 SoftQuad. ``The SGML Primer.'' 3rd ed., SoftQuad Inc.,
 1991. <URL:http://www.sq.com/>
 [ISO-646]
 ISO/IEC 646:1991 Information technology -- ISO 7-bit
 coded character set for information interchange
 <URL:http://www.iso.ch/cate/d4777.html>
 [ISO-10646]
 ISO/IEC 10646-1:1993 Information technology -- Universal
 Multiple-Octet Coded Character Set (UCS) -- Part 1:
 Architecture and Basic Multilingual Plane
 <URL:http://www.iso.ch/cate/d18741.html>
 [ISO-8859-1]
 ISO 8859. International Standard -- Information
 Processing -- 8-bit Single-Byte Coded Graphic Character
 Sets -- Part 1: Latin Alphabet No. 1, ISO 8859-1:1987.
 <URL:http://www.iso.ch/cate/d16338.html>
 [SGML]
 ISO 8879. Information Processing -- Text and Office
 Systems - Standard Generalized Markup Language (SGML),
 1986. <URL:http://www.iso.ch/cate/d16387.html>
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12. Acknowledgments
 The HTML document type was designed by Tim Berners-Lee at CERN
 as part of the 1990 World Wide Web project. In 1992, Dan
 Connolly wrote the HTML Document Type Definition (DTD) and a
 brief HTML specification.
 Since 1993, a wide variety of Internet participants have
 contributed to the evolution of HTML, which has included the
 addition of in-line images introduced by the NCSA Mosaic
 software for WWW. Dave Raggett played an important role in
 deriving the FORMS material from the HTML+ specification.
 Dan Connolly and Karen Olson Muldrow rewrote the HTML
 Specification in 1994. The document was then edited by the HTML
 working group as a whole, with updates being made by Eric
 Schieler, Mike Knezovich, and Eric W. Sink at Spyglass, Inc.
 Finally, Roy Fielding restructured the entire draft into its
 current form.
 Special thanks to the many active participants in the HTML
 working group, too numerous to list individually, without whom
 there would be no standards process and no standard. That this
 document approaches its objective of carefully converging a
 description of current practice and formalization of HTML's
 relationship to SGML is a tribute to their effort.
12.1. Authors' Addresses
 Tim Berners-Lee
 Director, W3 Consortium
 MIT Laboratory for Computer Science
 545 Technology Square
 Cambridge, MA 02139, U.S.A.
 Tel: +1 (617) 253 9670
 Fax: +1 (617) 258 8682
 Email: timbl@w3.org
 Daniel W. Connolly
 Research Technical Staff, W3 Consortium
 MIT Laboratory for Computer Science
 545 Technology Square
 Cambridge, MA 02139, U.S.A.
 Fax: +1 (617) 258 8682
 Email: connolly@w3.org
 URI: http://www.w3.org/hypertext/WWW/People/Connolly/
13. The HTML Coded Character Set
 This list details the code positions and characters of the HTML
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 document character set, specified in 9.5, "SGML Declaration for
 HTML". This coded character set is based on [ISO-8859-1].
 REFERENCE DESCRIPTION
 -------------- -----------
 &#00; - &#08; Unused
 &#09; Horizontal tab
 &#10; Line feed
 &#11; - &#12; Unused
 &#13; Carriage Return
 &#14; - &#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; - &#159; Unused
 &#160; Non-breaking Space
 &#161; Inverted exclamation
 &#162; Cent sign
 &#163; Pound sterling
 &#164; General currency sign
 &#165; Yen sign
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 &#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
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 &#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. Proposed Entities
 The HTML DTD references the ``Added Latin 1'' entity set, which
 only supplies named entities for a subset of the non-ASCII
 characters in [ISO-8859-1], namely the accented characters. The
 following entities should be supported so that all ISO 8859-1
 characters may only be referenced symbolically. The names for
 these entities are taken from the appendixes of [SGML].
 <!ENTITY nbsp CDATA "&#160;" -- no-break space -->
 <!ENTITY iexcl CDATA "&#161;" -- inverted exclamation mark -->
 <!ENTITY cent CDATA "&#162;" -- cent sign -->
 <!ENTITY pound CDATA "&#163;" -- pound sterling sign -->
 <!ENTITY curren CDATA "&#164;" -- general currency sign -->
 <!ENTITY yen CDATA "&#165;" -- yen sign -->
 <!ENTITY brvbar CDATA "&#166;" -- broken (vertical) bar -->
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 <!ENTITY sect CDATA "&#167;" -- section sign -->
 <!ENTITY uml CDATA "&#168;" -- umlaut (dieresis) -->
 <!ENTITY copy CDATA "&#169;" -- copyright sign -->
 <!ENTITY ordf CDATA "&#170;" -- ordinal indicator, feminine -->
 <!ENTITY laquo CDATA "&#171;" -- angle quotation mark, left -->
 <!ENTITY not CDATA "&#172;" -- not sign -->
 <!ENTITY shy CDATA "&#173;" -- soft hyphen -->
 <!ENTITY reg CDATA "&#174;" -- registered sign -->
 <!ENTITY macr CDATA "&#175;" -- macron -->
 <!ENTITY deg CDATA "&#176;" -- degree sign -->
 <!ENTITY plusmn CDATA "&#177;" -- plus-or-minus sign -->
 <!ENTITY sup2 CDATA "&#178;" -- superscript two -->
 <!ENTITY sup3 CDATA "&#179;" -- superscript three -->
 <!ENTITY acute CDATA "&#180;" -- acute accent -->
 <!ENTITY micro CDATA "&#181;" -- micro sign -->
 <!ENTITY para CDATA "&#182;" -- pilcrow (paragraph sign) -->
 <!ENTITY middot CDATA "&#183;" -- middle dot -->
 <!ENTITY cedil CDATA "&#184;" -- cedilla -->
 <!ENTITY sup1 CDATA "&#185;" -- superscript one -->
 <!ENTITY ordm CDATA "&#186;" -- ordinal indicator, masculine -->
 <!ENTITY raquo CDATA "&#187;" -- angle quotation mark, right -->
 <!ENTITY frac14 CDATA "&#188;" -- fraction one-quarter -->
 <!ENTITY frac12 CDATA "&#189;" -- fraction one-half -->
 <!ENTITY frac34 CDATA "&#190;" -- fraction three-quarters -->
 <!ENTITY iquest CDATA "&#191;" -- inverted question mark -->
 <!ENTITY Agrave CDATA "&#192;" -- capital A, grave accent -->
 <!ENTITY Aacute CDATA "&#193;" -- capital A, acute accent -->
 <!ENTITY Acirc CDATA "&#194;" -- capital A, circumflex accent -->
 <!ENTITY Atilde CDATA "&#195;" -- capital A, tilde -->
 <!ENTITY Auml CDATA "&#196;" -- capital A, dieresis or umlaut mark -->
 <!ENTITY Aring CDATA "&#197;" -- capital A, ring -->
 <!ENTITY AElig CDATA "&#198;" -- capital AE diphthong (ligature) -->
 <!ENTITY Ccedil CDATA "&#199;" -- capital C, cedilla -->
 <!ENTITY Egrave CDATA "&#200;" -- capital E, grave accent -->
 <!ENTITY Eacute CDATA "&#201;" -- capital E, acute accent -->
 <!ENTITY Ecirc CDATA "&#202;" -- capital E, circumflex accent -->
 <!ENTITY Euml CDATA "&#203;" -- capital E, dieresis or umlaut mark -->
 <!ENTITY Igrave CDATA "&#204;" -- capital I, grave accent -->
 <!ENTITY Iacute CDATA "&#205;" -- capital I, acute accent -->
 <!ENTITY Icirc CDATA "&#206;" -- capital I, circumflex accent -->
 <!ENTITY Iuml CDATA "&#207;" -- capital I, dieresis or umlaut mark -->
 <!ENTITY ETH CDATA "&#208;" -- capital Eth, Icelandic -->
 <!ENTITY Ntilde CDATA "&#209;" -- capital N, tilde -->
 <!ENTITY Ograve CDATA "&#210;" -- capital O, grave accent -->
 <!ENTITY Oacute CDATA "&#211;" -- capital O, acute accent -->
 <!ENTITY Ocirc CDATA "&#212;" -- capital O, circumflex accent -->
 <!ENTITY Otilde CDATA "&#213;" -- capital O, tilde -->
 <!ENTITY Ouml CDATA "&#214;" -- capital O, dieresis or umlaut mark -->
 <!ENTITY times CDATA "&#215;" -- multiply sign -->
 <!ENTITY Oslash CDATA "&#216;" -- capital O, slash -->
 <!ENTITY Ugrave CDATA "&#217;" -- capital U, grave accent -->
 <!ENTITY Uacute CDATA "&#218;" -- capital U, acute accent -->
 <!ENTITY Ucirc CDATA "&#219;" -- capital U, circumflex accent -->
 <!ENTITY Uuml CDATA "&#220;" -- capital U, dieresis or umlaut mark -->
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 <!ENTITY Yacute CDATA "&#221;" -- capital Y, acute accent -->
 <!ENTITY THORN CDATA "&#222;" -- capital THORN, Icelandic -->
 <!ENTITY szlig CDATA "&#223;" -- small sharp s, German (sz ligature) -->
 <!ENTITY agrave CDATA "&#224;" -- small a, grave accent -->
 <!ENTITY aacute CDATA "&#225;" -- small a, acute accent -->
 <!ENTITY acirc CDATA "&#226;" -- small a, circumflex accent -->
 <!ENTITY atilde CDATA "&#227;" -- small a, tilde -->
 <!ENTITY auml CDATA "&#228;" -- small a, dieresis or umlaut mark -->
 <!ENTITY aring CDATA "&#229;" -- small a, ring -->
 <!ENTITY aelig CDATA "&#230;" -- small ae diphthong (ligature) -->
 <!ENTITY ccedil CDATA "&#231;" -- small c, cedilla -->
 <!ENTITY egrave CDATA "&#232;" -- small e, grave accent -->
 <!ENTITY eacute CDATA "&#233;" -- small e, acute accent -->
 <!ENTITY ecirc CDATA "&#234;" -- small e, circumflex accent -->
 <!ENTITY euml CDATA "&#235;" -- small e, dieresis or umlaut mark -->
 <!ENTITY igrave CDATA "&#236;" -- small i, grave accent -->
 <!ENTITY iacute CDATA "&#237;" -- small i, acute accent -->
 <!ENTITY icirc CDATA "&#238;" -- small i, circumflex accent -->
 <!ENTITY iuml CDATA "&#239;" -- small i, dieresis or umlaut mark -->
 <!ENTITY eth CDATA "&#240;" -- small eth, Icelandic -->
 <!ENTITY ntilde CDATA "&#241;" -- small n, tilde -->
 <!ENTITY ograve CDATA "&#242;" -- small o, grave accent -->
 <!ENTITY oacute CDATA "&#243;" -- small o, acute accent -->
 <!ENTITY ocirc CDATA "&#244;" -- small o, circumflex accent -->
 <!ENTITY otilde CDATA "&#245;" -- small o, tilde -->
 <!ENTITY ouml CDATA "&#246;" -- small o, dieresis or umlaut mark -->
 <!ENTITY divide CDATA "&#247;" -- divide sign -->
 <!ENTITY oslash CDATA "&#248;" -- small o, slash -->
 <!ENTITY ugrave CDATA "&#249;" -- small u, grave accent -->
 <!ENTITY uacute CDATA "&#250;" -- small u, acute accent -->
 <!ENTITY ucirc CDATA "&#251;" -- small u, circumflex accent -->
 <!ENTITY uuml CDATA "&#252;" -- small u, dieresis or umlaut mark -->
 <!ENTITY yacute CDATA "&#253;" -- small y, acute accent -->
 <!ENTITY thorn CDATA "&#254;" -- small thorn, Icelandic -->
 <!ENTITY yuml CDATA "&#255;" -- small y, dieresis or umlaut mark -->
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