Movatterモバイル変換


[0]ホーム

URL:



Hypertext Markup Language (HTML)          Tim Berners-Lee, CERNInternet Draft                          Daniel Connolly, AtriumIIIR Working Group                                    June 1993Hypertext Markup Language (HTML)   A Representation of Textual Information and MetaInformation                   for Retrieval and InterchangeStatus of this Document   This document is an Internet Draft. Internet Draft. working   documents of the Internet Engineering Task Force (IETF), its Areas,   and its Working Groups.  Note that other groups may also distribute   working documents as Internet Drafts.   Internet Drafts are working documents valid for a maximum of six   months. Internet Drafts may be updated, replaced, or  obsoleted by   other documents at any time.  It is not appropriate to use Internet   Drafts as reference material or to cite them other than as a   "working draft" or "work in progress".   Distribution of this document is unlimited.   The document is a   draft form of a standard for interchange of information on the   network which is proposed  to be registered as a MIME (RFC1341)   content type. Please send comments to timbl@info.cern.ch or the   discussion list www-talk@info.cern.ch.   This is version 1.1 of this specification. This document is   available in hypertext on the World-Wide Web ashttp://info.cern.ch/hypertext/WWW/MarkUp/HTML.htmlAbstract   HyperText Markup Language (HTML)  can be used to represent      Hypertext news, mail, online documentation, and collaborative      hypermedia;      Menus of  options;      Database query results;      Simple structured documents with inlined graphics.      Hypertext views of existing bodies of information   The World Wide Web (W3) initiative links related information   throughout the globe.  HTML provides one simple format forBerners-Lee and Connolly                                             1Internet Draft      Hypertext Markup Language (HTML)           June 1993   throughout the globe.  HTML provides one simple format for   providing linked information, and  all W3 compatible programs are   required to be capable of handling HTML.    W3 uses an Internet   protocol (Hypertext Transfer Protocol, HTTP), which allows transfer   representations to be negotiated between client and server, the   result being returned in an extended MIME message.  HTML is   therefore just one, but an important one, of the representations   used with W3.   HTML is proposed as a  MIME content type.   HTML refers to the URL specification of RFCxxxx.   Implementations of HTML parsers and generators can be found in the   various W3 servers and browsers, in the public domain W3 code, and   may also be built using various public domain SGML parsers such as   [SGMLS] .  HTML is an SGML document type with fairly generic   semantics appropriate for representing information from a wide   range of applications.  It is more generic than many specific SGML   applications, but is still completely device-independent.                           IN THIS DOCUMENT   This document contains the following parts:  Vocabulary             used in this document, degrees of imperative.  HTML and MIME          with discussion of character sets.  HTML and SGML          and the reelationship between them,  and                         Structured text : an introduction for                         beginners to SGML.  HTML Elements           A list with description, example, and                         typical rendering.  HTML Entities           Entities used to describe characters.  The HTML DTD            The text of the SGML DTD for HTML  Link relationship values .                          A provisional list. Not part of the                         standard.  Registration Authority                          The authority for extending lists of valid                         vales.  References              to related documents  Authors addresses       Contact information.   tableofcontentsBerners-Lee and Connolly                                             2Internet Draft      Hypertext Markup Language (HTML)           June 1993Vocabulary   This specification uses the words below with the precise meaning   given.  Representation          The encoding of information for interchange.                         For example, HTML is a representation of                         hypertext.  Rendering               The form of presentation to information to                         the human reader.  IMPERATIVES  may                     The implementation is not obliged to follow                         this in  any way.  must                    If this is not followed, the implementation                         does not conform to this specification.  shall                   as "must"  should                  If this is not followed, though the                         implementation officially conforms to the                         standard, undesirable results may occur in                         practice.  typical                 Typical rendering is described for many                         elements. This is not a mandatory part of the                         standard but is given as guidance for                         designers and to help explian the uses for                         which the elements were intended.  NOTES   Sections marked "Note:" are not mandatory parts of the   specification but for guidance only.  STATUS OF FEATURES  Mainstream              All parsers must recognise these features.                         Features are mainstream unless otherwise                         mentioned.  Extra                   Standard HTML features which may safely be                         ignored by parsers. It is legal to ignore                         these, treat the contents as though the tags                         were not there. (e.g. EM, and any undefined                         elements)  Obsolete                Not standard HTML.  Parsers should implementBerners-Lee and Connolly                                             3Internet Draft      Hypertext Markup Language (HTML)           June 1993                         these features as far as poosible in order to                         preverve back-compatibility with oprevious                         versions of this specification.                            HTML AND MIME   The definition of the HTML content subtype is  MIME Type name          text  MIME subtype name:      html  Required parameters:    none  Optional parameters:    charsetCharacter sets   The base character set (the SGML BASESET) for HTML is ISO Latin-1.   This is the set refered to by any numeric character references. The   actual character set used in the representation of an HTML document   may be ISO Latin 1, or its 7-bit subset which is ASCII.  There is   no obligation for an HTML document to contain any characters above   decimal 127.   It is possible that  a transport medium such as   electronic mail imposes constraints on the number of bits in a   representation of a document, though the HTTP access protocol used   by W3 always allows 8 bit transfer.   When an HTML document is encoded using 7-bit characters, then the   mechanisms of character references and entity references may be   used to encode characters in the upper half of the ISO Latin-1 set.    In this way, documents may be prepared which are suitable for   mailing through 7-bit limited systems.                            HTML AND SGML   The HyperText Markup Language is defined in terms of the ISO   Standard Generalized Markup Language [SGML]. SGML is a system for   defining structured document types and markup languages to   represent instances of those document types.   Every SGML document has three parts:      An SGML declaration, which binds SGML processing quantities and      syntax token names to specific values. For example, the SGML      declaration in the HTML DTD specifies that the string that opens      a tag is 60;/ and the maximum length of a name is 40 characters.      A prologue including one or more document type declarations,      which specifiy the element types, element relationships andBerners-Lee and Connolly                                             4Internet Draft      Hypertext Markup Language (HTML)           June 1993      attributes, and references that can be represented by markup.      The HTML DTD specifies, for example, that the HEAD element      contains at most one TITLE element.      An instance, which contains the data and markup of the document.   We use the term HTML to mean both the document type and the markup   language for representing instances of that document type.   All HTML documents share the same SGML declaration an prologue.   Hence implementations of the WorldWide Web generally only transmit   and store the instance part of an HTML document. To construct an   SGML document entity for processing by an SGML parser, it is   necessary to prefix the text from ``HTML DTD'' on page 10 to the   HTML instance.   Conversely, to implement an HTML parser, one need only implement   those parts of an SGML parser that are needed to parse an instance   after parsing the HTML DTD.Structured Text   An HTML instance is like a text file, except that some of the   characters are interpreted as markup. The markup gives structure to   the document.   The instance represents a hierarchy of elements. Each element has a   name , some attributes , and some content. Most elements are   represented in the document as a start tag, which gives the name   and attributes, followed by the content, followed by the end tag.   For example:                <HTML>                 <TITLE>                  A sample HTML instance                 </TITLE>                 <H1>                  An Example of Structure                 </H1>                 Here's a typical paragraph.                 <P>                 <UL>                  <LI>                  Item one has an                  <A NAME="anchor">                   anchor                  </A>                  <LI>                  Here's item two.                 </UL>                </HTML>Berners-Lee and Connolly                                             5Internet Draft      Hypertext Markup Language (HTML)           June 1993   Some elements (e.g. P, LI) are empty. They have no content. They   show up as just a start tag.   For the rest of the elements, the content is a sequence of data   characters and nested elements.  Note that the HTML DTD in fact   severely limits the amount of nesting which is allowed: most things   cannot be nested, in fact.   No elements may be recursively nested.     Anchors and character highlighting may be put inside other   constructs.  TAGS   Every element starts with a tag, and every non-empty element ends   with a tag. Start tags are delimited by < and >, and end tags are   delimited by </ and >.    Names   The element name immediately follows the tag open delimiter. Names   consist of a letter followed by up to 33 letters, digits, periods,   or hyphens. Names are not case sensitive.    Attributes   In a start tag, whitespace and attributes are allowed between the   element name and the closing delimiter. An attribute consists of a   name, an equal sign, and a value. Whitespace is allowed around the   equal sign.   The value is specified in a string surrounded by single quotes or a   string surrounded by double quotes. (See: other tolerated forms @@)   The string is parsed like RCDATA (see below ) to determine the   attribute value. This allows, for example, quote characters in   attribute values to be represented by character references.   The length of an attribute value (after parsing) is limited to 1024   characters.  ELEMENT TYPES   The name of a tag refers to an element type declaration in the HTML   DTD. An element type declaration associates an element name with      A list of attributes and their types and statuses      A content type (one of EMPTY, CDATA, RCDATA, ELEMENT, or MIXED)      which determines the syntax of the element's content      A content model, which specifies the pattern of nested elements      and data    Empty ElementsBerners-Lee and Connolly                                             6Internet Draft      Hypertext Markup Language (HTML)           June 1993   Empty elements have the keyword EMPTY in their declaration. For   example:        <!ELEMENT NEXTID - O EMPTY>        <!ATTLIST NEXTID N NUMBER #REQUIRED>   This means that the follwing:        <nextid n=''27''>   is legal, but these others are not:        <nextid>        <nextid n=''abc''>    Character Data   The keyword CDATA indicates that the content of an element is   character data. Character data is all the text up to the next end   tag open delimter-in-context. For example:<!ELEMENT XMP - - CDATA>   specifies that the following text is a legal XMP element:        <xmp>Here's an example. It looks like it has        <tags> and <!--comments-->        in it, but it does not. Even this        </ is data.</xmp>   The string </ is only recognized as the opening delimiter of an end   tag when it is ``in context,'' that is, when it is followed by a   letter. However, as soon as the end tag open delimiter is   recognized, it terminates the CDATA content. The following is an   error:        <xmp>There is no way to represent </end> tags        in CDATA </xmp>    Replaceable Character Data   Elements with RCDATA content behave much like thos with CDATA,   except for character references and entity references. Elements   declared like:<!ELEMENT TITLE - - RCDATA>   can have any sequence of characters in their content.      Character ReferencesBerners-Lee and Connolly                                             7Internet Draft      Hypertext Markup Language (HTML)           June 1993   To represent a character that would otherwise be recognized as   markup, use a character referece. The string &# signals a character   reference when it is followed by a letter or a digit. The delimiter   is followed by the decimal character number and a semicolon. For   example:<title>You can even represent &#60;/end> tags in RCDATA </title>      Entity References   The HTML DTD declares entities for the less than, greater than, and   ampersand characters and each of the ISO Latin 1 characters so that   you can reference them by name rather than by number.   The string & signals an entity reference when it is followed by a   letter or a digit. The delimiter is followed by the entity name and   a semicolon. For example:Kurt G&ouml;del was a famous logician and mathemetician.  Note:                   To be sure that a string of characters has                         no markup, HTML writers should represent all                         occurences of <, >, and & by character or                         entity references.    Element Content   Some elements have, in stead of a keyword that states the type of   content, a content model, which tells what patterns of data and   nested elements are allowed. If the content model of an element   does not include the symbol #PCDATA , the content is element   content.   Whitespace in element content is considered markup and ignored. Any   characters that are not markup, that is, data characters, are   illegal.   For example:<!ELEMENT HEAD - - (TITLE? & ISINDEX? & NEXTID? & LINK*)>   declares an element that may be used as follows:<head> <isindex> <title>Head Example</title></head>   But the following are illegal:<head> no data allowed! </head><head><isindex><title>Two isindex tags</title><isindex></head>Berners-Lee and Connolly                                             8Internet Draft      Hypertext Markup Language (HTML)           June 1993    Mixed Content   If the content model includes the symbol #PCDATA, the content of   the element is parsed as mixed content. For example:<!ELEMENT PRE - - (#PCDATA | A | B | I | U | P)+><!ATTLIST PRE        WIDTH NUMBER #implied        >   This says that the PRE element contains one or more A, B, I, U, or   P elements or data characters. Here's an example of a PRE element:<pre><b>NAME</b>    cat -- concatenate<a href=''terms.html#file''>files</a><b>EXAMPLE</b>    cat <xyz</pre>   The content of the above PRE element is:      A B element      The string ``   cat -- concatenate''      An A element      The string ``\n''      Another B element      The string ``\n   cat <xyz''  COMMENTS AND OTHER MARKUP   To include comments in an HTML document that will be ignored by the   parser, surround them with <!-- and -->. After the comment   delimiter, all text up to the next occurence of -- is ignored.   Hence comments cannot be nested. Whitespace is allowed between the   closing -- and >. (But not between the opening <! and --.)   For example:<HEAD><TITLE>HTML Guide: Recommended Usage</TITLE><!-- $Id: recommended.html,v 1.3 93/01/06 18:38:11 connolly Exp $ --></HEAD>   There are a few other SGML markup constructs that are deprecated or   illegal.Berners-Lee and Connolly                                             9Internet Draft      Hypertext Markup Language (HTML)           June 1993  Delimiter               Signals...  <?                      Processing instruction. Terminated by >.  <![                     Marked section. Marked sections are                         deprecated. See the SGML standard for                         complete information.  <!                      Markup declaration. HTML defines no short                         reference maps, so these are errors.                         Terminated by >.  LINE BREAKS   A line break character is considered markup (and ignored) if it is   the first or last piece of content in an element. This allows you   to write either<PRE>some example text</pre>   or<pre>some example text</pre>   and these will be processed identically.   Also, a line that's not empty but contains no content will be   ignored altogether. For example, the element<pre><!-- this line is ignored, including the linebreak character -->first linethird line<!-- the following linebreak is content: -->fourth line<!-- this one's ignored cuz it's the last piece of content: --></pre>   contains only the strings first line third line fourth line.  SPACES AND TABS   Space characters must be rendered as horizontal white space.  In   HTML, multiple spaces should be rendered as proportionally larger   spaces.Berners-Lee and Connolly                                             10Internet Draft      Hypertext Markup Language (HTML)           June 1993   The rendering of a horizontal tab (HT) character is not defined,   and HT should therefore not be used, except within a PRE (or   obsolete XMP, LISTING or PLAINTEXT) element.   Neither spaces nor tabs should be used to make SGML source layout   more attractive or easier to read.  SUMMARY OF MARKUP SIGNALS   The following delimiters may signal markup, depending on context.  Delimiter               Signals  <!--                    Comment  &#                      Character reference  &                       Entity reference  </                      End tag  <!                      Markup declaration  ]]>                     Marked section close (an error)  <                       Start tag                            HTML ELEMENTS   This is a list of elements used in the HTML language.  Documents   should (but need not absolutely) contain an initial HEAD element   followed by a BODY element.    Old style documents may contain a just the contents of the normal   HEAD and BODY elements, in any order. This is deprecated but must   be supported by parsers.   See also:  Status of elementsProperties of the whole document   Properties of the whole document are defined by the following   elements. They should appear within the HEAD element.  Their order   is not significant.  TITLE                   The title of the document  ISINDEX                 Sent by a server in a searchable document  NEXTID                  A parameter used by editors to generate                         unique identifiersBerners-Lee and Connolly                                             11Internet Draft      Hypertext Markup Language (HTML)           June 1993  LINK                    Relationship between this document and                         another. See also the Anchor element ,                         Relationships .  A document may have many                         LINK elements.  BASE                    A record of the URL of the document when                         savedText formatting   These are elements which occur within the BODY element of a   document. Their order is the logical order in which the elements   should be rendered on the output device.  Headings                Several levels of heading are supported.  Anchors                 Sections of text which form the beginning                         and/or end of hypertext links are called                         "anchors" and defined by the A tag.  Paragraph marks         The P element marks the break between two                         paragraphs.  Address style           An ADDRESS element is displayed in a                         particular style.  Blockquote style        A block of text quoted from another source.  Lists                   Bulleted lists, glossaries, etc.  Preformatted text       Sections in fixed-width font for                         preformatted text.  Character highlighting                          Formatting elements which do not cause                         paragraph breaks.Graphics  IMG                     The IMG tag allows inline graphics.Obsolete elements   The other elements are obsolete but should be recognised by parsers   for back-compatibility.HEAD   The HEAD element contains all information about the document in   general.  It does not contain any text which is part of the   document: this is in the BODY. Within the head element, onlyBerners-Lee and Connolly                                             12Internet Draft      Hypertext Markup Language (HTML)           June 1993   certain elements are allowed.BODY   The BODY element contains all the information which is part of the   document, as opposed information about the document which is in the   HEAD .   The elements within the BODY element are in the order in which they   should be presented to the reader.   See the list of things which are allowed within a BODY element .Anchors   An anchor is a piece of text which marks the beginning and/or the   end of a hypertext link.   The text between the opening tag and the closing tag is either the   start or destination (or both) of a link. Attributes of the anchor   tag are as follows.  HREF                    OPTIONAL. If the HREF attribute is present,                         the anchor is sensitive text: the start of a                         link. If the reader selects this text,  (s)he                         should be presented with another document                         whose network address is defined by the value                         of the HREF attribute . The format of the                         network address is specified elsewhere . This                         allows for the form HREF="#identifier" to                         refer to another anchor in the same document.                         If the anchor is in another document, the                         attribute is a relative name , relative to                         the documents address (or specified base                         address if any).  NAME                    OPTIONAL. If present, the  attribute NAME                         allows the anchor to be the destination of a                         link. The value of the attribute is an                         identifier for the anchor.  Identifiers are                         arbitrary strings  but must be unique within                         the HTML document.   Another document can                         then make a reference explicitly to this                         anchor by putting the identifier after the                         address, separated by a hash sign .  REL                     OPTIONAL. An attribute REL may give the                         relationship (s) described by the hypertext                         link. The value is a comma-separated list of                         relationship values.   Values and their                         semantics will be registered by the HTML                         registration authority. The defaultBerners-Lee and Connolly                                             13Internet Draft      Hypertext Markup Language (HTML)           June 1993                         relationship if none other is given is void.                         REL should not be present unless HREF is                         present. See Relationship values , REV .  REV                     OPTIONAL. The same as REL , but the                         semantics of the link type are in the reverse                         direction.  A link from A to B with REL="X"                         expresses the same relationship as a link                         from B to A with REV="X".   An anchor may                         have both REL and REV attributes.  URN                     OPTIONAL. If present, this specifies a                         uniform resource number for the document. See                         note .  TITLE                   OPTIONAL. This is informational only. If                         present the value of this field should equal                         the value of the TITLE of the document whose                         address is given by the HREF attribute. See                         note .  METHODS                 OPTIONAL. The value of this field is a                         string which if present must be a comma                         separated list of HTTP METHODS supported by                         the object for public use.  See note .   All attributes are optional, although one of NAME and HREF is   necessary for the anchor to be useful. See also: LINK .  EXAMPLE OF USE:        See <A HREF="http://info.cern.ch/">CERN</A>'s information for        more details.        A <A NAME=serious>serious</A> crime is one which is associated        with imprisonment.                        ...        The Organisation may refuse employment to anyone convicted        of a <a href="#serious">serious</A> crime.  NOTE: UNIVERSAL RESOURCE NUMBERS   URNs are provided to allow a document to be recognised if duplicate   copies are found.  This should save a client implementation from   picking up a copy of something it already has.   The format of URNs is under discussion (1993) by various working   groups of the Internet Engineering Task Force.  NOTE:  TITLE ATTRIBUTE OF LINKS   The link may carry a TITLE attribute which should if present giveBerners-Lee and Connolly                                             14Internet Draft      Hypertext Markup Language (HTML)           June 1993   the title of the document whose address is given by the HREF   attribute.   This is useful for at least two reasons      The browser software may chose to display the title of the      document as a preliminary to retrieving it, for example as a      margin note or on a small box while the mouse is over the      anchor, or during document fetch.      Some documents -- mainly those which are not marked up text,      such as graphics, plain text and also  Gopher menus, do not come      with a title themselves, and so putting a title in the link is      the only way to give them a title. This is how Gopher works.      Obviously it leads to duplication of data, and so it is      dangerous to assume that the title attribute of the link is a      valid and unique title for the destination document.  NOTE: METHODS ATTRIBUTE OF LINKS   The METHODS attributes of anchors and links are used to provide   information about the functions which the user may perform on an   object. These are more accurately given by the HTTP protocol when   it is used, but it may, for similar reasons as for the TITLE   attribute, be useful to include the information in advance in the   link.   For example, The browser may chose a different rendering as a   function of the methods allowed (for example something which is   searchable may get a different icon)Address   This element is for address information, signatures, authorship,   etc, often at the top or bottom of a document.  TYPICAL RENDERING   Typically, an address element is italic and/or right justified or   indented.  The address element implies a paragraph break. Paragraph   marks within the address element do not cause extra white space to   be inserted.  EXAMPLES OF USE:                <ADDRESS><A HREF="Author.html">A.N.Other</A></ADDRESS>                <ADDRESS>                Newsletter editor<p>                J.R. Brown<p>                JimquickPost News, Jumquick, CT 01234<p>Berners-Lee and Connolly                                             15Internet Draft      Hypertext Markup Language (HTML)           June 1993                Tel (123) 456 7890                </ADDRESS>BASE   This element allows the URL of the document itself to be recorded   in situations in which the document may be read out of context.   URLs within the  document may be in a "partial" form relative  to   this base address.   Where the base address is not specified, the reader will use the   URL it used to access the document to resolve any relative URLs.   The one attribute is:  HREF                    the URLBLOCKQUOTE   The BLOCKQUOTE element allows text quoted from another source to be   rendered specially.  TYPICAL RENDERING   A typical rendering might be a slight extra left and right indent,   and/or italic font.  BLOCKQUOTE causes a paragraph break, and   typically a line or so of white space will be allowed between it   and any text before or after it.   Single-font rendition may for example put a vertical line of ">"   characters down the left margin to indicate quotation in the   Internet mail style.  EXAMPLEI think it ends<BLOCKQUOTE>Soft you now, the fair Ophelia. Nymph, in thy orisons,be all my sins remembered.</BLOCKQUOTE>but I am not sure.Headings   Six levels  of heading are supported. (Note that a hypertext node   within a hypertext work tends to need less levels of  heading than   a work whose only structure is given by the nesting of headings.)   A heading element implies all the font changes, paragraph breaks   before and after, and white space (for example) necessary to render   the heading. Futher character emphasis or paragraph marks are not   required in HTML.Berners-Lee and Connolly                                             16Internet Draft      Hypertext Markup Language (HTML)           June 1993   H1 is the highest level of heading, and is recommened for the start   of a hypertext node.   It is suggested that the the text of  the   first heading be suitable for a reader who is already browsing in   related information, in contrast to the title tag which should   identify the node in a wider context.   The heading elements are                <H1>, <H2>, <H3>, <H4>, <H5>, <H6>   It is not normal practice to jump from one header to a header level   more than one below, for example for follow an H1 with an H3.   Although this is legal, it is discouraged, as it may prodcue   strange results for example when generating other representations   from the HTML.  EXAMPLE:                <H1>This is a heading</H1>                Here is some text                <H2>Second level heading</H2>                Here is some more text.  PARSER NOTE:   Parsers should not require any specific order to heading elements,   even if the heading level increases by more than one between   successive headings.  TYPICAL RENDERING  H1                      Bold very large font, centered. One or two                         lines clear space between this and anything                         following.  If printed on paper, start new                         page.  H2                      Bold, large font,, flush left against left                         margin, no indent. One or two clear lines                         above and below.  H3                      Italic, large font, slightly indented from                         the left margin. One or two clear lines above                         and below.  H4                      Bold, normal font, indented more than H3.                         One clear line above and below.  H5                      Italic, normal font, indented as H4.  One                         clear line above.  H6                      Bold, indented same as normal text, moreBerners-Lee and Connolly                                             17Internet Draft      Hypertext Markup Language (HTML)           June 1993                         than H5. One clear line above.   These typical values are just an indication, and it is up to the   designer of the presentation software to define the styles.  The   reader may have options to customise these.  When writing   documents, you should assume that whatever is done it is designed   to have the same sort of effect as the styles above.   The rendering software is responsible for generating suitable   vertical white space between elements, so it is NOT normal or   required to follow a heading element with a paragraph mark.IMG: Embedded Images   Status: Extra   The IMG element allows another document to be inserted inline.  The   document is normally an icon or small graphic, etc. This element is   NOT intended for embedding other HTML text.   Browsers which are not able to display inline images ignore IMG   elements. Authors should note that some browsers will be able to   display (or print) linked graphics but not inline graphics.  If the   graphic is essential, it may be wiser to make a link to it rather   than to put it inline.  If the graphic is essentially decorative,   then IMG is appropriate.   The IMG element is empty: it has no closing tag. It has two   attributes:  SRC                     The value of this attribute is the URL of                         the document to be embedded. Its syntax is                         the same as that of the HREF attribute of the                         A tag. SRC is mandatory.  ALIGN                   Take values TOP or MIDDLE or BOTTOM,                         defining whether the tops or middles of                         bottoms of the graphics and text should be                         aligned vertically.   Note that IMG elements are allowed within anchors.  EXAMPLE        Warning: < IMG SRC ="triangle.gif"> This must be done by a        qualified technician.        < A HREF="Go">< IMG SRC ="Button"> Press to start</A>Berners-Lee and Connolly                                             18Internet Draft      Hypertext Markup Language (HTML)           June 1993ISINDEX   This element informs the reader that the document is an index   document. As well as reading it, the reader may use a keyword   search.   The node may be queried with a keyword search by suffixing the node   address with a question mark, followed by a list of keywords   separated by plus signs. See the network address format .   Note that this tag is normally generated automatically by a server.    If it is added by hand to an HTML document, then the client  will   assume that the server can handle a search on the document.   Obviously the server must have this capability for it to work:   simply adding <ISINDEX> in the document is not enough to make   searches happen if the server does not have a search engine!   Status: standard.  EXAMPLE OF USE:                <ISINDEX>LINK   The LINK element occurs within the HEAD element of an HTML   document. It is used to indicate a relationship between the   document and some other object.  A document may have any number of   LINK elements.   The LINK element is empty, but takes the same attributes as the   anchor element .   Typical  uses are to indicate authorship, related indexes and   glossaries, older or more recent versions, etc.  Links can indicate   a static tree structure in which the document was authored by   pointing to a "parent" and "next" and "previous" document, for   example.   Servers may also allow links to be added by those who do not have   the right to alter the body of a document.Forms of list in HTML  GLOSSARIES   A glossary (or definition list) is a list of paragraphs each of   which has a short title alongside it. Apart from glossaries, this   element is useful for presenting a set of named elements to the   reader. The elements within a glossary follow are  DT                      The "term", typically placed in a wide left                         indentBerners-Lee and Connolly                                             19Internet Draft      Hypertext Markup Language (HTML)           June 1993  DD                      The "definition", which may wrap onto many                         lines   These elements must appear in pairs. Single occurences of DT   without a following DD are illegal.  The one attribute which DL can   take is  COMPACT                 suggests that a compact rendering be used,                         because the enclosed elements are                         individually small, or the whole glossary is                         rather large, or both.    Typical rendering   The definition list DT, DD pairs are arranged vertically.   For   each pair, the DT element is on the left, in a column of about a   third of the display area, and the DD element is in the right hand   two thirds of the display area.  The DT term is normally small   enough to fit on one line within the left-hand column. If it is   longer, it will either extend acrosss the page, in which case the   DD section is moved down to separate them, or it is wrapped onto   successive lines of the left hand column.   White space is typically left between successive DT,DD pairs unless   the COMPACT attribute is given.  The COMPACT attribute is   appropriate for lists which are long and/or have DT,DD pairs which   each take only a line or two.  It is of course possible for the   rendering software to discover these cases itself and make its own   decisions, and this is to be encouraged.   The COMPACT attribute may also reduce the width of the left-hand   (DT) column.    Examples of use        <DL>        <DT>Term the first<DD>definition paragraph is reasonably        long but is still diplayed clearly        <DT>Term2 follows<DD>Definition of term2        </DL>        <DL COMPACT>        <DT>Term<DD>definition pagagraph        <DT>Term2<DD>Definition of term2        </DL>  LISTSBerners-Lee and Connolly                                             20Internet Draft      Hypertext Markup Language (HTML)           June 1993   A list is a sequence of paragraphs, each of which may be preceded   by a special mark or sequence number. The syntax is:                <UL>                <LI> list element                <LI> another list element ...                </UL>   The opening list tag  may be any of UL, OL, MENU or DIR.  It must   be immediately followed by the first list element.    Typical rendering   The representation of the list is not defined here, but a bulleted   list for unordered lists,  and a sequence of numbered paragraphs   for an ordered list would be quite appropriate. Other possibilities   for interactive display include embedded scrollable browse panels.   List elements with typical rendering are:  UL                      A list of multi-line paragraphs, typically                         separated by some white space and/or marked                         by bullets, etc.  OL                      As UL, but the paragraphs are typically                         numbered in some way to indicate the order as                         significant.  MENU                    A list of smaller paragraphs. Typically one                         line per item, with a style more compact than                         UL.  DIR                     A list of short elements, typically less                         than 20 characters.  These may be arranged in                         columns across the page, typically 24                         character in width. If the rendering software                         is able to optimise the column width as                         function of the widths of individual                         elements, so much the better.    Example of use                <OL>                <LI> When you get to the station, leave                by the southern exit, on platform one.                <LI>Turn left to face toward the mountain                <LI>Walk for a mile or so until you reach the                "Asquith Arms" then                <LI>Wait and see...                </OL>                < MENU >Berners-Lee and Connolly                                             21Internet Draft      Hypertext Markup Language (HTML)           June 1993                <LI>The oranges should be pressed fresh                <LI>The nuts may come from a packet                <LI>The gin must be good quality                </MENU>                < DIR >                <LI>A-H<LI>I-M                <LI>M-R<LI>S-Z                </DIR>Next ID   This tag takes a  single attribute which is the number of the next   document-wide numeric identifier to be allocated of the form z123.   When modifying a document, old anchor ids should not be reused, as   there may be references stored elsewhere which point to them.  This   is read and generated by hypertext editors. Human writers of HTML   usually use mnemonic alphabetical identifiers. Browser software may   ignore this tag.  EXAMPLE OF USE:                <NEXTID N=27>P: Paragraph mark   The empty P element indicates a paragraph break. The exact   rendering of this (indentation,  leading, etc) is not defined here,   and may be a function of other tags, style sheets etc.   <P> is used between two pieces of text which otherwise would be   flowed together.   You do NOT need to use <P>  to put white space around heading,   list, address or blockquote elements which imply a paragraph break.   It is the responsability of the rendering software to generate that   white space.   A paragraph mark which is preceded or followed by   such elements which imply a paragraph break is has undefined effect   and should be avoided.  TYPICAL RENDERING   Typically, <P> will generate a small vertical space (of a line or   half a line) between the paragraphs. This is not the case   (typically) within ADDRESS  or (ever) within PRE elements.    With   some implementations, in normal text, <P> may generate a small   extra left indent on the first line.  EXAMPLES OF USEBerners-Lee and Connolly                                             22Internet Draft      Hypertext Markup Language (HTML)           June 1993        <h1>What to do</h1>        This is a one paragraph.< p >This is a second.        < P >        This is a third.  BAD EXAMPLE        <h1><P>What not to do</h1>        <p>I found that on my XYZ browser it looked prettier to        me if I put some paragraph marks        <p>        <ul><p><li>Around lists, and        <li>After headings.        </ul>        <p>        None of the paragraph marks in this example should        be there.PRE: Preformatted text   Preformatted elements in HTML are displayed with text in a fixed   width font, and so are suitable for text which has been formatted   for a teletype by some existing formatting system.   The optional attribute is:  WIDTH                  This attribute gives the maximum number of                         characters which will occur on a line.  It                         allows the presentation system to select a                         suitable font and indentation. Where the                         WIDTH attribute is not recognised, it is                         recommened that a width of 80 be assumed.                         Where WIDTH is supported, it is recommeded                         that at least widths of 40, 80 and 132                         characters be presented optimally, with other                         widths being rounded up.   Within a PRE element,      Line boundaries within the text are rendered as a move to the      beginning of the next line, except for one immediately following      or immediately preceding a tag.       The <p> tag should not be used. If found, it should be rendered      as a move to the beginning of the next line.      Anchor elements and character highlighting elements may be used.Berners-Lee and Connolly                                             23Internet Draft      Hypertext Markup Language (HTML)           June 1993      Elements which define paragraph formatting (Headings, Address,      etc) must not be used.      The ASCII Horizontal Tab (HT) character must be interpreted as      the smallest positive nonzero number of spaces which will leave      the number of characters so far on the line as a multiple of 8.      Its use is not recommended however.    Example of use                        <PRE WIDTH="80">                        This is an example line                        </PRE>    Note: Highlighting   Within a preformatted element,  the constraint that the rendering   must be on a fixed horizontal character pitch may limit or prevent   the ability of the renderer to render highlighting elements   specially.    Note: Margins   The above references to the "beginning of a new line" must not be   taken as implying that the renderer is forbidden from using a   (constant) left indent for rendering preformatted text.   The left   indent may of course be constrained by the width required.TITLE   The title of a document is specified by the TITLE element.  The   TITLE element should occur in the HEAD of the document.   There may only be one title in any document. It should identify the   content of the document in a fairly wide context.   The title is not part of the text of the document, but is a   property of the whole document. It may not contain anchors,   paragraph marks, or highlighting. The title may be used to identify   the node in a history list, to label the window displaying the   node, etc. It is not normally displayed in the text of a document   itself. Contrast titles with headings .  The title should ideally   be less than 64 characters in length.  That is, many applications   will display document titles in window titles, menus, etc where   there is only limited room.  Whilst there is no limit on the length   of a title (as it may be automatically generated from other data),   information providers are warned that it may be truncated if long.    Examples of use   Appropriate titles might beBerners-Lee and Connolly                                             24Internet Draft      Hypertext Markup Language (HTML)           June 1993                <TITLE>Rivest and Neuman. 1989(b)</TITLE>   or                <TITLE>A Recipe for Maple Syrup Flap-Jack</TITLE>   or                <TITLE>Introduction -- AFS user's Guide</TITLE>   Examples of inappropriate titles are those which are only   meaningful within context,                <TITLE>Introduction</TITLE>   or too long,        <TITLE>Remarks on the Quantum-Gravity effects of "Bean        Pole" diversification in Mononucleosis patients in Developing        Countries under Economic Conditions Prevalent during        the Second half of the Twentieth Century, and Related Papers:        a Summary</TITLE>Character highlighting   Status: Extra   These elements allow sections of text to be formatted in a   particular way, to provide emphasis, etc.  The tags do NOT cause a   paragraph break, and may be used on sections of text within   paragraphs.   Where not supported by implementations, like all tags, these tags   should be ignored but the content rendered.   All these tags have related closing tags, as in                This is <EM>emphasised</EM> text.   Some of these styles are more explicit than others about how they   should be physically represented.  The logical styles should be   used wherever possible, unless for example it is necessary to refer   to the formatting in the text. (Eg, "The italic parts are   mandatory".)    Note:   Browsers unable to display a specified style may render it in someBerners-Lee and Connolly                                             25Internet Draft      Hypertext Markup Language (HTML)           June 1993   alternative, or the default, style, with some loss of qualtity for   the reader. Some implementations may ignore these tags altogether,   so information providers should attempt not to rely on them as   essential to the information content.   These element names are derived from TeXInfo macro names.  PHYSICAL STYLES  TT                      Fixed-width typewriter font.  B                       Boldface, where available, otherwise                         alternative mapping allowed.  I                       Italic font (or slanted if italic                         unavailable).  U                       Underline.  LOGICAL STYLES  EM                      Emphasis, typically italic.  STRONG                  Stronger emphasis, typically bold.  CODE                    Example of code. typically monospaced font.                         (Donot confuse with  PRE)  SAMP                    A sequence of litteral characters.  KBD                     in an instruction manual, Text typed by a                         user.  VAR                     A variable name.  DFN                     The defining instance of a term.  Typically                         bold or bold italic.  CITE                    A citation. Typically italic.  EXAMPLES OF USE        This text contains an <em>emphasised</em> word.        <strong>Don't assume</strong> that it will be italic!        It was made using the <CODE>EM</CODE> element. A citation is        typically italic and has no formal necessary structure:        <cite>Moby Dick</cite> is a book title.Obsolete elementsBerners-Lee and Connolly                                             26Internet Draft      Hypertext Markup Language (HTML)           June 1993   The following elements of HTML are obsolete.  It is recommended   that client implementors implement the obsolete forms for   compatibility with old servers.    Plaintext   Status: Obsolete .   The empty PLAINTEXT tag terminates the HTML entity. What follows is   not SGML. In stead, there's an old HTTP convention that what   follows is an ASCII  (MIME "text/plain") body.   An example if its use is:                        <PLAINTEXT>                        0001 This is line one of a ling listing                        0002 file from <any@host.inc.com> which is sent   This tag allows the rest of a file to be read efficiently without   parsing. Its presence is an optimisation. There is no closing tag.   The rest of the data is not in SGML.    XMP and LISTING:   Example sections   Status:  Obsolete . This are in use and should be recognised by   browers. New servers should use <PRE> instead.   These styles allow text of fixed-width characters to be embedded   absolutely as is into the document. The syntax is:                        <LISTING>                                ...                        </LISTING>   or                        <XMP>                                ...                        </XMP>   The text between these tags is to be portrayed in a fixed width   font, so that any formatting done by character spacing on   successive lines will be maintained. Between the opening and   closing tags:      The text may contain any ISO Latin printable characters, but not      the end tag opener. (See Historical note )      Line boundaries are significant, except any occuring immediately      after the opening tag or before the closing tag. and are to be      rendered as a move to the start of a new line.Berners-Lee and Connolly                                             27Internet Draft      Hypertext Markup Language (HTML)           June 1993      The ASCII Horizontal Tab (HT) character must be interpreted as      the smallest positive nonzero number of spaces which will leave      the number of characters so far on the line as a multiple of 8.      Its use is not recommended however.   The LISTING element is portrayed so that at least 132 characters   will fit on a line.  The XMP elemnt is portrayed in a font so that   at least 80 characters will fit on a line but is otherwise   identical to LISTING.    Highlighted Phrase HP1 etc   Status: Obsolete . These tags like all others should be ignored if   not implemented. Replaced will more meaningful elements -- see   character highlighting .      Examples of use:                <HP1>...</HP1>   <HP2>... </HP2> etc.    Comment element   Status: Obsolete   A comment element used for bracketing off unneed text and comment   has been intriduced in some browsers but will be replaced by the   SGML command feature in new implementations.  HISTORICAL NOTE: XMP AND LISTING   The XMP and LISTING elements used historically to have non SGML   conforming specifications, in that the text could contain any ISO   Latin printable characters, including the tag opener, so long as it   does not contain the closing tag in full.   This form is not supported by SGML and so is not the specified HTML   interpretation.  Providers should be warned that implemntations may   vary on how they interpret end tags apparently within these   elements                               ENTITIES   The following entity names are used in HTML , always prefixed by   ampersand (&) and followed by a semicolon as shown.  They represent   particular graphic characters which have special meanings in places   in the markup, or may not be part of the character set available to   the writer.  &lt;                    The less than sign <  &gt;                    The "greater than" sign >  &amp;                   The ampersand sign & itself.Berners-Lee and Connolly                                             28Internet Draft      Hypertext Markup Language (HTML)           June 1993  &quot;                  The double quote sign "   Also allowed are references to any of the ISO Latin-1 alphabet,   using the entity names in the following table.ISO Latin 1 character entities   This list is derived from "ISO 8879:1986//ENTITIES Added Latin   1//EN".  &AElig;                capital AE diphthong (ligature)  &Aacute;               capital A, acute accent  &Acirc;                capital A, circumflex accent  &Agrave;               capital A, grave accent  &Aring;                capital A, ring  &Atilde;               capital A, tilde  &Auml;                 capital A, dieresis or umlaut mark  &Ccedil;               capital C, cedilla  &ETH;                  capital Eth, Icelandic  &Eacute;               capital E, acute accent  &Ecirc;                capital E, circumflex accent  &Egrave;               capital E, grave accent  &Euml;                 capital E, dieresis or umlaut mark  &Iacute;               capital I, acute accent  &Icirc;                capital I, circumflex accent  &Igrave;               capital I, grave accent  &Iuml;                 capital I, dieresis or umlaut mark  &Ntilde;               capital N, tilde  &Oacute;               capital O, acute accent  &Ocirc;                capital O, circumflex accent  &Ograve;               capital O, grave accentBerners-Lee and Connolly                                             29Internet Draft      Hypertext Markup Language (HTML)           June 1993  &Oslash;               capital O, slash  &Otilde;               capital O, tilde  &Ouml;                 capital O, dieresis or umlaut mark  &THORN;                capital THORN, Icelandic  &Uacute;               capital U, acute accent  &Ucirc;                capital U, circumflex accent  &Ugrave;               capital U, grave accent  &Uuml;                 capital U, dieresis or umlaut mark  &Yacute;               capital Y, acute accent  &aacute;               small a, acute accent  &acirc;                small a, circumflex accent  &aelig;                small ae diphthong (ligature)  &agrave;               small a, grave accent  &aring;                small a, ring  &atilde;               small a, tilde  &auml;                 small a, dieresis or umlaut mark  &ccedil;               small c, cedilla  &eacute;               small e, acute accent  &ecirc;                small e, circumflex accent  &egrave;               small e, grave accent  &eth;                  small eth, Icelandic  &euml;                 small e, dieresis or umlaut mark  &iacute;               small i, acute accent  &icirc;                small i, circumflex accent  &igrave;               small i, grave accent  &iuml;                 small i, dieresis or umlaut markBerners-Lee and Connolly                                             30Internet Draft      Hypertext Markup Language (HTML)           June 1993  &ntilde;               small n, tilde  &oacute;               small o, acute accent  &ocirc;                small o, circumflex accent  &ograve;               small o, grave accent  &oslash;               small o, slash  &otilde;               small o, tilde  &ouml;                 small o, dieresis or umlaut mark  &szlig;                small sharp s, German (sz ligature)  &thorn;                small thorn, Icelandic  &uacute;               small u, acute accent  &ucirc;                small u, circumflex accent  &ugrave;               small u, grave accent  &uuml;                 small u, dieresis or umlaut mark  &yacute;               small y, acute accent  &yuml;                 small y, dieresis or umlaut mark                             THE HTML DTD   The HTML DTD follows . Its relationship to the content of an SGML   document is explained in the section "HTML and SGML" .<!SGML  "ISO 8879:1986"--        Document Type Definition for the HyperText Markup Language        as used by the World Wide Web application (HTML DTD).        NOTE: This is a definition of HTML with respect to        SGML, and assumes an understaning of SGML terms.--CHARSET         BASESET  "ISO 646:1983//CHARSET                   International Reference Version (IRV)//ESC 2/5 4/0"         DESCSET  0   9   UNUSED                  9   2   9                  11  2   UNUSEDBerners-Lee and Connolly                                             31Internet Draft      Hypertext Markup Language (HTML)           June 1993                  13  1   13                  14  18  UNUSED                  32  95  32                  127 1   UNUSEDCAPACITY        SGMLREF                TOTALCAP        150000                GRPCAP          150000SCOPE    DOCUMENTSYNTAX         SHUNCHAR CONTROLS 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18                           19 20 21 22 23 24 25 26 27 28 29 30 31 127255         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                  NAMELEN  34                  TAGLVL   100                  LITLEN   1024                  GRPGTCNT 150                  GRPCNT   64FEATURES  MINIMIZE    DATATAG  NO    OMITTAG  NO    RANK     NO    SHORTTAG NO  LINK    SIMPLE   NO    IMPLICIT NO    EXPLICIT NO  OTHER    CONCUR   NO    SUBDOC   NO    FORMAL   YESBerners-Lee and Connolly                                             32Internet Draft      Hypertext Markup Language (HTML)           June 1993  APPINFO    NONE><!DOCTYPE HTML [<!-- $Id: html.dtd,v 1.3 93/01/06 18:38:10 connolly Exp $--><!--    Regarding clause 6.1, SGML Document:        [1] SGML document = SGML document entity,            (SGML subdocument entity |            SGML text entity | non-SGML data entity)*        The role of SGML document entity is filled by this DTD,        followed by the conventional HTML data stream.--><!-- DTD definitions --><!ENTITY % heading "H1|H2|H3|H4|H5|H6" ><!ENTITY % list " UL | OL | DIR | MENU "><!ENTITY % literal " XMP | LISTING "><!ENTITY % headelement         " TITLE | NEXTID | ISINDEX" ><!ENTITY % bodyelement         "P | A | %heading |         %list | DL | HEADERS | ADDRESS | PRE | BLOCKQUOTE        | %literal"><!ENTITY % oldstyle "%headelement | %bodyelement | #PCDATA"><!-- Characters from various Latin alphabets. --><!ENTITY % ISOlat1 PUBLIC        "ISO 8879:1986//ENTITIES Added Latin 1//EN">%ISOlat1;<!-- Document Element --><!ELEMENT HTML 0 0  ( HEAD | BODY | %oldstyle )*><!ELEMENT HEAD - -  ( TITLE ? & ISINDEX ? & NEXTID ? & LINK *                              & BASE ? )><!ELEMENT TITLE - -  RCDATA          -- The TITLE element is not considered part of the flow of text.             It should be displayed, for example as the page header or             window title.Berners-Lee and Connolly                                             33Internet Draft      Hypertext Markup Language (HTML)           June 1993          --><!ELEMENT ISINDEX - 0 EMPTY          -- WWW clients should offer the option to perform a search on             documents containing ISINDEX.          --><!ELEMENT NEXTID - 0 EMPTY><!ATTLIST NEXTID N NAME #REQUIRED          -- The number should be a name suitable for use             for the ID of a new element. When used, the value             has its numeric part incremented. EG Z67 becomes Z68          --><!ELEMENT LINK - 0 EMPTY><!ATTLIST LINK        NAME NMTOKEN #IMPLIED        HREF %URL; #IMPLIED        REL CDATA #IMPLIED -- type of relashionship        REV CDATA #IMPLIED -- type of relashionship                              to referent data:                                PARENT CHILD, SIBLING, NEXT, TOP,                                DEFINITION, UPDATE, ORIGINAL etc. --        URN CDATA #IMPLIED -- universal resource number --        TITLE CDATA #IMPLIED -- advisory only --        METHODS NAMES #IMPLIED -- supported public methods of the object:                                        TEXTSEARCH, GET, HEAD, ... --        ><!ELEMENT BASE - 0 EMPTY>    -- Reference context for URLS --<!ATTLIST BASE        HREF %URL; #IMPLIED        ><!ENTITY % inline "EM | TT | STRONG | B | I | U |                        CODE | SAMP | KBD | KEY | VAR | DFN | CITE "        ><!ELEMENT (%inline;) - - (#PCDATA)><!ENTITY % text "#PCDATA | IMG | %inline;"><!ELEMENT BODY - -  (%bodyelement|%text;)*>Berners-Lee and Connolly                                             34Internet Draft      Hypertext Markup Language (HTML)           June 1993<!ENTITY % URL "CDATA"        -- The term URL means a CDATA attribute           whose value is a Uniform Resource Locator,           as defined. (A URN may also be usable here when defined.)        --><!ELEMENT A     - -  (#PCDATA)><!ATTLIST A        NAME NMTOKEN #IMPLIED        HREF %URL ; #IMPLIED        REL CDATA #IMPLIED        REV CDATA #IMPLIED -- type of relashionship:                                PARENT CHILD, SIBLING, NEXT, TOP,                                 DEFINITION, UPDATE, ORIGINAL etc.--        URN CDATA #IMPLIED -- uniform resource number --        TITLE CDATA #IMPLIED -- advisory only --        METHODS NAMES #IMPLIED -- supportedpublic methods of the object:                                        TEXTSEARCH, GET, HEAD, ... --        ><!ELEMENT IMG    - 0 EMPTY --  Embedded image --><!ATTLIST IMG        SRC %URL ; #IMPLIED     -- URL of document to embed --        ><!ENTITY % htext "A | %text"><!ELEMENT P     - 0 EMPTY -- separates paragraphs --><!ELEMENT ( %heading )  - -  (%text;|A)+><!ELEMENT HEADERS - - (DT | #PCDATA | DD | A)+><!ELEMENT DL    - -  (DT | DD | P | %htext;)*><!--    Content should match ((DT,(%htext;)+)+,(DD,(%htext;)+))        But mixed content is messy.  --><!ELEMENT DT    - 0 EMPTY><!ELEMENT DD    - 0 EMPTY><!ELEMENT (%list) - -  (%htext;|LI|P)+><!--    Content should match ((LI,(%htext;)+)+)        But mixed content is messy.  --><!ATTLIST (%list)        COMPACT NAME #IMPLIED -- COMPACT, etc.--        ><!ELEMENT LI    - 0 EMPTY><!ELEMENT BLOCKQUOTE - - (%htext;|P)+Berners-Lee and Connolly                                             35Internet Draft      Hypertext Markup Language (HTML)           June 1993        -- for quoting some other source --><!ATTLIST BLOCKQUOTE        ><!ELEMENT ADDRESS - - (%htext;|P)+><!ELEMENT PRE - - (%htext|P)+><!ATTLIST PRE        WIDTH NUMBER #implied        ><!-- deprecated elements --><!ELEMENT (%literal) - -  RCDATA><!ELEMENT PLAINTEXT - 0 EMPTY><!-- Local Variables: --><!-- mode: sgml --><!-- compile-command: "sgmls -s -p " --><!-- end: -->]>                       LINK RELATIONSHIP VALUES   Status: This list is not part of the standard.  It is intended to   illustrate the use of link relationships and to provide a framework   for further development.   Additions to this list will be controlled by the HTML registration   authority . Experimental values may be used on the condition that   they begin with "X-".   These values of the REL attribute of hypertext links have a   significance defined here, and may be treated in special ways by   HTML applications.   These relationships relate whole documents (objects), rather than   particular anchors within them. If the relationship value is used   with a link between anchors rather than whole documents, the   semantics are considered to apply to the documents.   In the explanations which follows, A is the source document of the   link and B is the destination document specified by the HREF   attribute.   A relationship marked "Acyclic" has the property that no sequence   of links with that relationship may be followed from any document   back to itself. These types of links may therefore be used to   define trees.Berners-Lee and Connolly                                             36Internet Draft      Hypertext Markup Language (HTML)           June 1993Relationships between documents   These relationships are between the documents themselves rather   than the subjects of the documents.  USEINDEX   B is a related index for a search by a user reading this document   who asks for an index search function.   A document may have any number of index links, causing several   indexes top be searched in a client-defined manner.   B must support SEARCH operations under its access protocol.  USEGLOSSARY   B is an index which should be used to resolve glossary queries in   the document. (Typically, a double-click on a word which is not   within an anchor).   A document may have any number of glossary links.  ANNOTATION   The information in B is additional to and subsidiary to that in A.   Annotation is used by one person to write the equivalent of "margin   notes" or other criticism on another's document, for example.   Example: The relationship between a newsgroup and its articles.   Acyclic.  REPLY   Similar to Annotation, but there is no suggestion that B is   subsidiary to A: A and B are on equal footings.   Example: The relationship between a mail message and its reply, a   news article and its reply.   Acyclic.  EMBED   If this link is followed, the node at the end of it is embedded   into the display of the source document.   Acyclic.  PRECEDESBerners-Lee and Connolly                                             37Internet Draft      Hypertext Markup Language (HTML)           June 1993   In an ordered structure defined by the author, A precedes B, B is   followed by A.   Acyclic.   Any document may only have one link of this relationship, and/or   one link of the reverse relationship.   Note: May be used to control navigational aids, generate printed   material, etc.  In conjunction with "subdocument", may be used to   define a tree such as a printed book made of hypertext document.   The document can only have one such tree.  SUBDOCUMENT   B is a lower part in the author's hierarchy to A.  Acyclic. See   also Precedes.  PRESENT   Whenever A is presented, B must also be presented.  This implies   that whenever A is retrieved, B must also be retrieved.  SEARCH   When the link is followed, the node B should be searched rather   than presented. That is, where the client software allows it, the   user should immediately be presented with a search panel and   prompted for text. The search is then performed without an   intermediate retrieval or presentation of the node B  SUPERSEDES   B is a previous version of  A.   Acyclic.  HISTORY   B is a list of versions of A   A link reverse link must exist from B to A and to all other known   versions of A.Relationships about subjects of documents   These relationships convey semantics about objects described by   documents, rather than the documents themselves.  INCLUDES   A includes B, B is part of A.  For example, a person described by   document A is a part of the group described by document B.Berners-Lee and Connolly                                             38Internet Draft      Hypertext Markup Language (HTML)           June 1993   Acyclic.  MADE   Person (etc) described by node A is author of, or is responsible   for B   This information can be used for protection, and informing authors   of interest, for sending mail to authors, etc.  INTERESTED   Person (etc) described by A is interested in node B   This information can be used for informing readers of changes.                        REGISTRATION AUTHORITY   The HTTP Registration Authority is responsible for maintaining   lists of:      Relationship names for link and anchor elements   It is proposed that the Internet Assigned Numbers Authority or   their successors take this role.   Unregistered values may be used for experimental purposes if they   are start with "X-".                              REFERENCES  SGML                    ISO 8879:1986, Information ProcessingText                         and Office SystemsStandard Generalized Markup                         Language (SGML).  sgmls                   an SGML parser by James Clark                         <jjc@jclark.com> derived from the ARCSGML                         parser materials which were written by                         Charles F. Goldfarb. The source is available                         on the ifi.uio.no FTP server in the directory                         /pub/SGML/SGMLS .  WWW                     The World-Wide Web , a global information                         initiative. For boostrap information, telnet                         info.cern.ch or find documents byftp://info.cern.ch/pub/www/doc  URL                     Universal Resource Locators. RFCxxx.                         Currently  available by anonymous FTP from                         info.cern.ch in /pub/ietf.Berners-Lee and Connolly                                             39Internet Draft      Hypertext Markup Language (HTML)           June 1993                          AUTHOR'S ADDRESSES   This document was prepared with the help and advice of many people   across the net.  Dan Connolly prepared the DTD and the section on   HTML and SGML whilst with Convex Computer Corporation of 3000   Waterview Parkway Richardson, TX 75083. He is now with Atrium   Technology Inc., and is not a current editor of the document.                                Tim Berners-Lee                Address         CERN                                1211 Geneva 23                                Switzerland                Telephone:      +41(22)767 3755                Fax:            +41(22)767 7155                email:          timbl@info.cern.ch                                Daniel Connolly                Address:        Atrium Technologies, Inc.                                5000 Plaza on the Lake, Suite 275                                Austin, TX 78746                                USA                email:          connolly@atrium.comBerners-Lee and Connolly                                             40
Datatracker

draft-ietf-iiir-html-00

This is an older version of an Internet-Draft whose latest revision state is "Expired".

DocumentDocument type
This is an older version of an Internet-Draft whose latest revision state is "Expired".
Expired & archived
Select version
Compare versions
Author
RFC streamIETF LogoIETF Logo
Other formats
Additional resources Mailing list discussion
Report a datatracker bug

[8]ページ先頭

©2009-2025 Movatter.jp