Re: popup chit chat (draft-ietf-html-relrev-00.txt)

Heikki Vesalainen (wes@clinet.fi)
Sun, 24 Mar 1996 16:03:23 -0800


Message-Id: <3155E2CB.4F1A@clinet.fi>
Date: Sun, 24 Mar 1996 16:03:23 -0800
From: Heikki Vesalainen <wes@clinet.fi>
To: The W3 HTML group <www-html@w3.org>
Subject: Re: popup chit chat (draft-ietf-html-relrev-00.txt)

This is a multi-part message in MIME format.

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Samuel Rinnetmaki wrote:
> I suggest you get your hands on the file:
>                 draft-ietf-html-relrev-00.txt

The file my friend Samuel was refering to is attached to this message.

-- 
Heikki Vesalainen
http://www.clinet.fi/~wes/
wes@clinet.fi

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                        INTERNET DRAFT

                   Hypertext links in HTML
                draft-ietf-html-relrev-00.txt

                            today

              Murray Maloney          Liam Quin
               SoftQuad Inc.         SoftQuad Inc.
               murray@sq.com          lee@sq.com

Status of this Memo
   This document is an Internet Draft.  Internet Drafts are
   working documents of the Internet Engineering Task Force
   (IETF), its Areas, and its Working Groups.  Note that other
   groups may also distribute working documents as Internet
   Drafts.

   Internet Drafts are draft documents valid for a maximum of six
   months.  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.'' Please check the 1id-abstracts.txt listing
   contained in the internet-drafts Shadow Directories on
   nic.ddn.mil, venera.isi.edu, nnsc.nsf.net, nic.nordu.net,
   ftp.nisc.sri.com, or munnari.oz.au to learn the current status
   of any Internet Draft.

   This is a working document only, it should neither be cited
   nor quoted in any formal document.

   This document will expire before 7 June 1996.

   Distribution of this document is unlimited.

   Please send comments to the author(s).

Table of Contents
   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .  2
   2.  Anchors and Targets . . . . . . . . . . . . . . . . . . . . .  3
      2a. Anchors  . . . . . . . . . . . . . . . . . . . . . . . . .  3
      2b. Targets  . . . . . . . . . . . . . . . . . . . . . . . . .  4
   3.  The LINK and A Elements and Their Attributes  . . . . . . . .  5
      3a. The LINK Element . . . . . . . . . . . . . . . . . . . . .  5
      3b. The A Element  . . . . . . . . . . . . . . . . . . . . . .  6
      3c. Common Attributes  . . . . . . . . . . . . . . . . . . . .  6
   4. The REL and REV Attribute Values . . . . . . . . . . . . . . .  8
      4a. Legacy . . . . . . . . . . . . . . . . . . . . . . . . . .  8
      4b. Browser-defined Links  . . . . . . . . . . . . . . . . . .  9
      4c. Navigational Node Links  . . . . . . . . . . . . . . . . .  9
      4d. Hierarchy Links  . . . . . . . . . . . . . . . . . . . . . 10
      4e. Sequence Links . . . . . . . . . . . . . . . . . . . . . . 11
      4f. Related Documents  . . . . . . . . . . . . . . . . . . . . 12
      4g. Meta Documents . . . . . . . . . . . . . . . . . . . . . . 14
      4f. Other REL and REV Values Under Discussion  . . . . . . . . 16
   5.  Hypertext Includes  . . . . . . . . . . . . . . . . . . . . . 18
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      5a. INCLUDE as a REL or REV Value  . . . . . . . . . . . . . . 18
      5b. INCLUDE as an Element  . . . . . . . . . . . . . . . . . . 19
      5c. SGML external entitities . . . . . . . . . . . . . . . . . 19
   6. Hypertext Paths  . . . . . . . . . . . . . . . . . . . . . . . 19
   7. Proposed New Attributes for A and LINK Elements  . . . . . . . 20
      7a. ACTION or STYLE or PROCESS or PRESENT  . . . . . . . . . . 20
      7b. TARGET . . . . . . . . . . . . . . . . . . . . . . . . . . 21
      7c. DINGBAT  . . . . . . . . . . . . . . . . . . . . . . . . . 21
      7d. HILITE or HIGHLIGHT  . . . . . . . . . . . . . . . . . . . 21
      7e. METHOD . . . . . . . . . . . . . . . . . . . . . . . . . . 22
      7f. SRC  . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
      7g. WHEN . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
      7h. OBSOLETES, UPDATES and DERIVED-FROM: . . . . . . . . . . . 23
   8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 23

Hypertext links in HTML

This is a discussion paper: It was initiated through discussion on the
HTML Working Group mailing list.

Hypertext link relationships, specified by using the REL and REV
attributes of the LINK and A elements, were conceived of as an early
feature of the HTML language.  Amidst all of the various and sundry
efforts that have been undertaken to advance HTML and the World Wide
Web, the definition of a small set of widely accepted hypertext
relationships has yet to be agreed upon and deployed in user agents.

Hypertext link relationships, and the attendant REL and REV attributes
of the LINK and A elements, are discussed in Dave Raggett's Internet
Draft on HTML 3.0.  In addition, The Santa Cruz Operation, Inc (SCO) has
developed an HTML user agent, based on Mosaic, which incorporates the
use of the REL attribute of the LINK element.

The first draft of this paper was based on Dave Raggett's paper and on
the author's experience with a partial implementation at SCO. Others
have contributed to the development of this paper through discussions on
the html-wg mailing list and through private correspondence with the
author.  (See the Acknowledgements section.)

1.  Introduction
   The hypertext link mechanism is the connective tissue used to weave
   the World Wide Web.  A hypertext link is an object which specifies
   a connection between any arbitrary addressable objects, locations,
   or resources.

   A hypertext link typically consists of an anchor and a target, each
   of which may be further classified and between which relationships
   may be identified. In HTML, there are several language elements
   which are used to identify anchors and targets and thus support the
   hypertext link mechanism.

   The anchor of a hypertext link is typically presented to the user,
   through an HTML user agent, as a highlighted object (a word, phrase,
   graphic image, etc.).  Not all anchors of hypertext links must be
   represented as highlighted within the document or the application.
   An HTML user agent may, as appropriate, act upon a hypertext link by
   taking immediate action, such as presenting a concurrent window. A
   user agent may, in some cases, simply ignore an anchor and its
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   hypertext link.

   An HTML user agent is free to provide whatever mechanism it chooses
   to allow the user to traverse from anchor to target.  Typically,
   graphical applications provide for user interaction via a pointing
   device such as a mouse.  Typically, non-graphical text-based
   applications provide for user interaction via keyboard and arrow
   selection.

   Different hypertext links may have different behavior associated
   with them.  For example, a link to a Table of Contents may be
   presented as an icon, with an appropriate label, in a tool bar.
   Another application may present the same link as a simultaneous view
   of the document in an alternate window or a concurrent pane.  A
   hypertext link may also initiate a software program, or present
   audio, graphics, video, print, speech synthesis or braille.

   HTML provides a mechanism for specifying the relationship between an
   anchor and a target as seen from either end  of the hypertext link.
   The LINK and the A elements each provide a REL and a REV attribute
   which may be set with values to identify these relationships.  The
   IMG element and the SRC attribute can also be used to form links.

   This purpose of this document is to discuss and formalize hypertext
   anchors as currently implemented on the World Wide Web, and to
   propose REL/REV relationships that are useful and consistent with
   current usage.  This paper is intended to describe hypertext links,
   anchors and targets, classes and relationships.  It is also intended
   to provide suggestions or hints for authors and publishers, and for
   developers of HTML user agents to guide them in using the hypertext
   link mechanism effectively.

   NOTE: This document does not address issues associated with
   non-practiced usages of hypertext anchors, in particular the
   inclusion/embedding of program applications (e.g. Java applets),
   within HTML documents.

2.  Anchors and Targets
   2a. Anchors
      An anchor is any object which acts as a hypertext link to a
      target. An anchor may be a highlighted phrase within an HTML
      document, an icon on an HTML user-agent tool-bar or menu item, an
      active graphic, or an image map.  An anchor may also be an object
      which is included by reference, such a graphic image.

      There are four ways to specify an anchor in HTML:
      * the A element
      * the LINK element
      * the SRC attribute as used on
	 * the IMG element
	 * the UL element (HTML 3.0 proposal)
	 * the LI element (HTML 3.0 proposal)
	 * the NOTE element (HTML 3.0 proposal)
      * the ISMAP attribute as used on the IMG element

      An anchor is typically specified using the A element. This form
      of anchor is used to highlight an object (word, phrase, graphic
      image, etc.) which may be activated by a user to traverse the
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      link by using the following form:
	 <A HREF="target">object to highlight</A>

      An anchor may also be specified using the LINK element. This form
      of anchor is used to establish a hypertext link between an entire
      HTML document and another addressable object or resource. A LINK
      element is considered document meta-information (it does not mark
      a link relationship specific to any part of the body), and is
      therefore restricted to lie within the document HEAD.  Because
      the LINK element is only allowed within the HEAD of an HTML
      document, and because it has no content, it is not usually
      represented within the body of an HTML document as seen through a
      user agent.  Its purpose is solely to inform the user agent that a
      link exists.  The user agent may process or ignore these links as
      it sees fit, but it may, for example, present an icon on a
      toolbar for the user to traverse the link.  An example of LINK
      usage is:
	<LINK HREF="chapter1.html" REL=PREVIOUS>
	<LINK HREF="chapter3.html" REL=NEXT>

      An anchor may also be specified using the IMG element. This form
      of anchor is used to establish a hypertext link to include a
      graphic image.  Its purpose it solely to inform the user agent
      that a graphic image may be placed at the current location if the
      user agent is capable of doing so, and if the user has enabled
      viewing of graphic images.  An example of this form of IMG usage
      is:
	  <IMG SRC="image.gif">

      An anchor may also be specified by providing a value to the SRC
      attribute on any HTML element which supports that attribute.
      For example:
          <NOTE CLASS=WARNING SRC=WARNING.gif> ... </NOTE>

      A specialized active hypertext link anchor known as an image map
      may be specified by using the IMG element in combination with the
      SRC and ISMAP attributes.  An example of this form of IMG usage
      is:
          <A HREF="..."><IMG SRC="image.gif" ISMAP></A>

   2b. Targets
      A target is any addressable object or resource which typically
      serves as the destination of a hypertext link.  The destination
      may be another HTML document, a fragment within the same or
      another HTML document, or any other type of object or resource.

      A target may also be an aggregate link which can be presented as
      a list of possible targets from which a user can select.  A Table
      of Contents may be an example of an aggregate link.  The result of
      a query is an other example.

      Any addressable object may serve as the target of a hypertext
      link. Typically, a target is addressed by specifying a URL/URI as
      the value of an HREF or SRC attribute on HTML elements which
      support those attributes.

      HTML also provides a number of language elements which may be
      used to identify a target within an HTML document and to specify
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      the base location from which relative addresses should be
      formed.

      There are four ways to specify a target within an HTML document:
      *  the BASE element
      *  the NAME attribute of the A element
      *  the ID attribute of various elements, including A and LINK
         (HTML 3.0 proposal)
      *  the NAME attribute of the LINK element

      The base location of a document may be recorded in the BASE
      element in the HEAD of the document. The base location is the
      address from which all relative URL addresses are to be formed.
      For example:
          <BASE HREF="http://server.domain/whatever">

      A target may be specified by surrounding any object (word,
      phrase, graphic image, etc.) with an A element having a non-null
      NAME attribute, and the target is considered to be the beginning
      of the encapsulated object.  For example:
          <A NAME="nametoken">target object</A>

      A target may also be specified by providing a value for the ID
      attribute on any HTML element which supports that attribute.
      For example:
          <P ID="PARA-1.1">

      A target may also be specified as an attribute to a LINK element.
      A LINK element may only be used within the head of an HTML
      document, and it has no content. For example:
          <HTML>
          <HEAD>
          <LINK NAME="THIS">
          <LINK NAME="THAT" HREF="THAT.html">
          </HEAD>

3.  The LINK and A Elements and Their Attributes
   The LINK and A elements share a set of common attributes.  Except
   where noted, the semantics of those attributes is the same.

   3a. The LINK Element
      The LINK element indicates a hypertext link relationship between
      the document in which it is found and some other object.  Any
      number of LINK elements may be used within the head of an HTML
      document.  The LINK element is empty (does not have a closing
      tag). The LINK element takes the same attributes as the A
      (anchor) element.

      The hypertext link described by the LINK element is not typically
      represented within the text area of an HTML user agent.  Instead,
      an HTML user agent is free to either ignore  any LINK element and
      the hypertext link associated with it, or to represent the
      hypertext link in some other way.

      Presenting hypertext links as active icons in a toolbar is one
      way to present them to the user.  Another may be to present the
      target document in a concurrent window, such as with a table of
      contents.
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   3b. The A Element
      The A element is used to indicate the start (anchor) or end
      (target) of a hypertext link within the body of an HTML
      document.

      The hypertext link described by the A element is typically
      represented as a highlighted object (word, phrase, graphical
      image, etc.) within the text area of an HTML user agent.

   3c. Common Attributes
      For the purposes of this discussion, the following is a list with
      descriptions of the most important common attributes.  All of the
      attributes listed here are part of HTML 2.0 except for CLASS, ID
      and MD, which are discussed  in Dave Raggett's Internet Draft on
      HTML 3.0.

      CLASS
	 The CLASS attribute value is used to subclass the hypertext
	 link.  The CLASS attribute is most often used as a generalized
	 identifier to which style information may be attached by a
	 stylesheet mechanism.

	 The CLASS attribute may also be used to subclass LINK
	 elements, thereby differentiating hypertext links with common
	 REL or REV values.  This may provide unambiguous syntax, for
	 example, for multiple LINK elements with REL=NEXT within a
	 document.  Thus, alternate paths through a document can be
	 coded within the document. For example:
	    <LINK REL=NEXT CLASS=NOVICE  HREF=... >
	    <LINK REL=NEXT CLASS=VETERAN HREF=... >
	    <LINK REL=NEXT CLASS=EXPERT  HREF=... >
	    <LINK REL=NEXT CLASS=GURU    HREF=... >

	  Multiple CLASS values may be specified.  The potential list of
	  CLASS attribute values is open-ended.  However, practical
	  application will likely require definition and specification
	  of at least a small set of accepted keywords, and agreement
	  on processing expectations for arbitrary keywords.  The
	  keywords used in the previous example are typical of the
	  type of keywords which may be specified, but are not
	  proposed.

       HREF
	  The HREF attribute value specifies the location  of a
	  destination or resource, expressed in the  Universal Resource
	  Identifier (URI) notation.  Only one HREF value may be
	  specified.  An HTML user agent may present the value of the
	  HREF attribute in an information area when the user positions
	  the mouse over the anchor or otherwise indicates interest in
	  the anchor.

       ID
	  The ID attribute specifies an SGML identifier used as the
	  target of hypertext links or for naming particular elements
	  in associated style sheets.  Only one ID value may be
	  specified.  The attribute value must be unique within the
	  document.
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       MD
	  The MD attribute specifies a message digest or cryptographic
	  checksum for the target of the hypertext link.  This attribute
	  is used by a user agent to verify that the linked object is
	  the same one that the author intended.

       NAME
	  The NAME attribute specifies a named location within an HTML
	  document and is used in forming addresses to target specific
	  locations within an HTML document.  Only one NAME value may be
	  specified. The attribute value must be unique within the
	  document.

       REL
	  The REL attribute specifies the relationship of the target to
	  the anchor.  For example, REL=NEXT is used to indicate that
	  the target is the next logical document in an author-
	  specified sequence.  The REL attribute can also be used to
	  support  search for links serving particular relationships.

	  Multiple REL values may be specified.  Aggregate links can be
	  formed by including multiple LINK elements with equivalent
	  REL values.  Activating the link, in that case, may lead to a
	  virtual menu from which the user can make a selection.

	  The nature of a link relationship is not always obvious from
	  the attribute value.  Section 4 (Meaning of REL and REV
	  Attribute Values) describes commonly accepted values.
	  Designers of HTML user agents can use these descriptions as a
	  guide to implementation of browser or agent behavior.

       REV
	  The REV attribute specifies the relationship of the anchor to
	  the target. For example, REV=TOP is used to indicate that the
	  anchor is the top of an author-specified  hierarchical tree
	  of which the target is a branch or node.

	  Multiple REV values may be specified.  A Table of Contents may
	  contain a series of anchors which specify REV=TOC.

	  The nature of a link relationship is not always obvious from
	  the attribute value.  Section 4 (Meaning of REL and REV
	  Attribute Values) describes commonly accepted values.
	  Designers of HTML user agents can use these descriptions as a
	  guide to implementation of browser or agent behavior.

       TITLE
	  The TITLE attribute  is typically used to describe the linked
	  object specified by the HREF attribute.  The attribute value
	  is a character string which may include spaces and
	  punctuation.  An HTML user agent may present the value of the
	  TITLE attribute in an information area when the user
	  positions the mouse over the anchor or otherwise indicates
	  interest in the anchor.  Authors/publishers can thereby
	  provide greater context to the user to aid them in making
	  decisions about whether to traverse a hypertext link.

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	  An HTML user agent may also use the value of the TITLE
	  attribute to set the value of an email subject field when the
	  HREF value uses the `mailto:' scheme.  In this way, the
	  subject field may be preset with value that the author's mail
	  agent can recognize and process.

      Although the HREF and TITLE attributes have been singled out in
      the list above, any of these attribute values may be presented in
      an information area when the user positions the mouse over the
      anchor or otherwise indicates interest in the anchor.  For
      example, an HTML user agent which is also an HTML editor may
      display the value of ID or NAME attributes.

4. The REL and REV Attribute Values

   The potential list of valid values for REL and REV is open-ended,
   and this document is not intended to preclude the use or adoption of
   other or additional values. In fact, it is anticipated that
   hypertext applications which support specific knowledge domains will
   need to develop specialized sets of keywords. It is hoped that the
   development of extensions will not occur in isolation, and that
   coordination of extensions among various interested parties will
   prevent namespace contention or collision.

   Further, HTML user agents should continue to be liberal in accepting
   new or alternate values, inasmuch as any name token is a legal
   value. The HTML specification declares that REL/REV values are SGML
   name tokens. That is, within the previously described syntactical
   constraints, a REL or REV relationship value may be any arbitrary,
   author-defined value that the author or publisher considers
   important. In some cases, the HTML user agent may choose to present
   relationships that it recognizes in a richer style,  while
   continuing to present unfamiliar ones in the default style.

   The REL and REV attributes are defined as NAMES  in the SGML DTD for
   the HyperText Markup Language (HTML). As such, the legal values
   which may be assigned to the REL or REV attribute are zero or more
   name tokens. Name tokens are case-insensitive, must begin with an
   alpha character, may include digits (0-9), period or hyphen, and may
   be separated by spaces. The name tokens listed and described in this
   section are being recommended as commonly accepted relationships
   between and among objects in a hypertext collection.

   When a single name token is specified as a REL or REV attribute,
   double quotes surrounding the attribute value are optional. When
   multiple name tokens are specified, double quotes are mandatory.
          <A REL="PARENT" HREF="..." > previous </A>
          <A REL="PARENT PREVIOUS" HREF="..." > previous </A>
          <A REL="SIBLING NEXT" HREF="..." > next </A>

   4a. Legacy
      The following are REL values which were known to be used as
      values of the REL and REV attributes on the World Wide Web in
      December 1995.

      MADE
	 The REV=MADE relationship has been used to identify the author
	 or "maker" of an HTML document.  Typical HREF values include a
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	 `mailto:' URI or the URL of the author's home page.  Example:
	    <A REV=MADE HREF="mailto:murray@sq.com">Author</A>

      NEXT/PREVIOUS/TOC/INDEX/NAVIGATOR
	 These values are described below, are used by SCO in its online
	 documentation and context- sensitive help system.

   4b. Browser-defined Links

      Some keywords are reserved and should not be used as REL/REV
      values.

      HTML user agents typically provide a mechanism for navigating
      through the recent history of a user's access to documents;
      traditionally these operations are referred to as "back" and
      "forward". These mechanisms allow a user to step back through the
      documents which led to the current location and then forward
      again to retrace the path. Additionally, most user agents provide
      a mechanism to immediately return to a user-defined location,
      traditionally referred to as the home page, or "home". Since
      these browser actions are internally implemented by the browser,
      REL/REV keywords associated with these relationships are
      disallowed.

      HOME
	 RESERVED.  Defined by the user (for example, using an
	 environment variable or preference, e.g. WWW_HOME).
	 This relationship may not be overridden; HTML user agents
	 should ignore any author-supplied REL=HOME setting.

      BACK
	 RESERVED.  Defined by the browser.  This relationship may not
	 be overridden; HTML user agents should ignore any
	 author-supplied REL=BACK setting.

      FORWARD
	 RESERVED.  Defined by the browser. This relationship may not
	 be overridden; HTML user agents should ignore any
	 author-supplied REL=FORWARD setting.

   4c. Navigational Node Links
      Navigational nodes are commonly used document objects which are
      designed by authors to assist the user  in navigating through a
      closed or extended document set.  The most familiar and common
      form of navigational node is a table of contents, which is a well
      known publishing device used for enumerating and ordering the
      contents of a closed document set.

      CONTENTS or TOC
         The TOC relationship identifies a Table of Contents.

	 When REL=TOC, the target document is the Table of Contents for
	 the current document, or for the collection of documents of
	 which the current document is a member.

	 When REV=TOC, the current document is a Table of Contents and
	 the target document is a related document.

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	 When REL=TOC and REV=TOC it indicates that the current
	 document is a Table of Contents and the target document is
	 also a Table of Contents.  Additional REL/REV values may be
	 used to specify the relationship between the two, such as
	 PARENT/CHILD.

	 If the hypertext link is specified with REL in a LINK element,
	 an HTML user agent may present an icon in a tool bar. Or, if
	 capable, an HTML user agent may present the Table of Contents
	 in a concurrent window or pane, highlighting the current
	 document.

      INDEX
	 The INDEX relationship identifies an index.

	 When REL=INDEX, the target document is an index for the
	 current document, or for the collection of documents of which
	 the current document is a member.

	 When REV=INDEX, the current document is an index. Additional
	 REL/REV values may be used to further specify the relationship
	 between the two ends of the link.

	 If the hypertext link is specified with REL in a LINK element,
	 an HTML user agent may present an icon in a tool bar.  An index
	 may be presented as an HTML document which is organized and
	 presented in a style reminiscent of a paper-based index.  An
	 index may also be presented as a form-based query into a full-
	 text search database.

      NAVIGATOR
	 The NAVIGATOR relationship identifies a navigational aid.

	 When REL=NAVIGATOR, the target document is a navigational aid.
	 A navigational aid may consist of a whole or partial Table of
	 Contents, a list of related documents, an indication of the
	 current document's location within a document hierarchy, or
	 any other information which may be useful to the user.

	 When REV=NAVIGATOR, the current document is a navigational aid.

	 If the hypertext link is specified with REL in a LINK element,
	 an HTML user agent may present an icon in a tool bar.

   4d. Hierarchy Links
      It is quite common for documents to be developed  or defined
      using a hierarchical model, or tree-like structure.  The keywords
      listed below may be used within HTML documents to identify the
      hierarchical relationship of closely related nodes, such as the
      immediate parent, siblings and children. In addition, the TOP
      keyword may be used to identify the logical top (or root,
      depending on your perspective) of a hierarchical or tree-like
      structure.

      The entire set of relationships may be used by a user agent to
      build a map of the hierarchical structure(s) of which the
      current document is a node.  Hypertext links to documents
      identified with PARENT and TOP values are more likely to be
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      accessible through an icon or other mechanism than documents
      identified with CHILD or SIBLING.

      CHILD          
	 The CHILD relationship identifies a subordinate or
	 subdocument. Any document may have multiple CHILD documents
	 within the same hierarchy.

	 When REL=CHILD, the target document is a hierarchical child,
	 or subdocument, of the current document.

	 When REV=CHILD, the current document is the hierarchical
	 child, or subdocument, of the target.

      PARENT
	 The PARENT relationship identifies the superior or container
	 node.

	 When REL=PARENT, the target document is the hierarchical
	 parent, or container, of the current document.

	 When REV=PARENT, the current document is the hierarchical
	 parent, or container, of the target.

	 If the hypertext link is specified with REL in a LINK element,
	 an HTML user agent may present an icon in a tool bar.

      SIBLING
	 The SIBLING relationship identifies a sibling in the current
	 hierarchy. Any document may have multiple SIBLING documents
	 within the same hierarchy.

	 When REL=SIBLING, the target document is a child of a common
	 parent, or a hierarchical peer of the current document.  REL
	 and REV have equivalent meanings for the SIBLING
	 relationship.

      TOP or ORIGIN
	 The TOP relationship identifies the logical top of a
	 hierarchical tree of which the current document is a branch.
	 BEGIN is a functional equivalent to TOP, if only one  of these
	 values is specified.

	 When REL=TOP, the target document is the logical top node of
	 the tree.  When REV=TOP, the current document is the logical
	 top of the tree.

	 If the hypertext link is specified with REL in a LINK element,
	 an HTML user agent may present an icon in a tool bar.

	 NOTE: ORIGIN has been suggested as an alternative to TOP to
	 provide metaphorical consistency with PARENT/CHILD/SIBLING.
	 Comments are encouraged.

   4e. Sequence Links
      Given a set of documents, it is possible and often desirable to
      specify linear sequences to navigate through the set.  A book, for
      example, is often organized as a linear sequence.  With sequence
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      links in each document, a user agent can step through or gather
      an entire book programmatically.

      BEGIN or FIRST
	 The BEGIN relationship identifies the author- defined start of
	 a sequence of documents of which the current document is a
	 node. TOP is a functional equivalent to BEGIN when only one of
	 these values is specified.

	 When REL=BEGIN, the target document is the beginning of the
	 sequence.  When REV=BEGIN, the current document is the
	 beginning of the sequence.

	 If the hypertext link is specified with REL in a LINK element,
	 an HTML user agent may present an icon in a tool bar.
      END or LAST
	 The END relationship identifies the author defined end of a
	 sequence of documents of which the current document is a node.
	 TOP is a functional equivalent to END when only one is
	 specified.

	 When REL=END, the target document is the end of the sequence.
	 When REV=END, the current document is the end of the sequence.

	 If the hypertext link is specified with REL in a LINK element,
	 an HTML user agent may present an icon in a tool bar.

      NEXT
	 The NEXT relationship identifies the next document in an
	 author-defined sequence of documents, such as a linear book.

	 When REL=NEXT, the target document is next after the current
	 document.  When REV=NEXT, the current document is next after
	 the target.

	 If the hypertext link is specified with REL in a LINK element,
	 an HTML user agent may present an icon in a tool bar.

      PREVIOUS or PREV
	 The PREVIOUS relationship identifies the previous document in
	 an author-defined sequence of documents, such as a linear
	 book.

	 When REL=PREVIOUS, the target document is previous to the
	 current document.

	 When REV=PREVIOUS, the current document is previous to the
	 target.

	 If the hypertext link is specified with REL in a LINK element,
	 an HTML user agent may present an icon in a tool bar.

   4f. Related Documents
      BIBLIOENTRY
	 The BIBLIOENTRY relationship identifies a bibliographic entry.

	 BIBLIOENTRY would most typically be specified on an A element,
	 as it would specify a hypertext link between a citation and a
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	 bibliographic entry describing the citation.  Example:
	     <A REL=BIBLIOENTRY HREF="biblio.html#V.Bush"><CITE>As We
	     May Think</CITE></A>

	 The resource identified by this link may take any form desired
	 by the author/publisher. A bibliographic entry may be presented
	 in the style of a paper-based bibliographic entry, or it may be
	 presented as the result of a database query.

      BIBLIOGRAPHY
	 The BIBLIOGRAPHY relationship identifies a bibliography.

	 The resource identified by this link may take any form desired
	 by the author/publisher. A bibliography may be presented as an
	 HTML document which is organized and presented in a style
	 reminiscent of a paper-based bibliography. A bibliography may
	 also be presented as a form-based query into a bibliographic
	 database.

	 If the hypertext link is specified with REL in a LINK element,
	 an HTML user agent may present a labeled icon in a tool bar.

      CITATION
	 The CITATION relationship identifies a bibliographic citation.

	 When REL=CITATION, the target is a bibliographic citation. The
	 anchor, in this case, may be a bibliographic entry. The anchor
	 may also be a reference, thus allowing the reader a way to
	 locate the citation:
	     ... as described by Tim Berners-Lee
	     <A REL=CITATION HREF=#TBL>[1]</A>
	     ...

	 When REV=CITATION, the anchor is a citation.  Typically, the
	 anchor would also be enclosed within a CITE element as shown in
	 the example below. The example shown here also corresponds to
	 the previous example, serving as its target by use of the NAME
	 attribute.
	     ... is described in Tim Berners-Lee's
	     <CITE><A NAME=TBL REV=CITATION HREF=./biblio/TBL > The
	     HyperText Markup Language </A> </CITE>
	     ...

	 NOTE: an alternative (and preferred) approach would be to add a
	 URI-valued attribute (HREF?) to the HTML CITE element.

      DEFINITION
	 The DEFINITION relationship identifies a definition of a term.

	 Definitions may be, but are not necessarily, contained within a
	 glossary.  DEFINITION would most typically be specified on an A
	 element, as it would specify a hypertext link from a term to
	 its definition.
	     <A REL=DEFINITION HREF="glossary.html#HTTP">HTTP</A>

      FOOTNOTE
	 The FOOTNOTE relationship identifies a footnote.

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	 When REL=FOOTNOTE is specified on an A element, the anchor is a
	 footnote marker and the target is a footnote. This can be used
	 to link from the footnote marker (or a highlighted word,
	 phrase, etc.) to an HTML document which contains the footnote
	 text, or to a portion of the same document (see REV=FOOTNOTE).

	 When REL=FOOTNOTE is specified on a LINK element, it can
	 specify a hypertext link to a set of footnotes which are
	 related to the current document, or to a set of end-notes.

	 When REV=FOOTNOTE is specified on an A element, the anchor is a
	 footnote; that is, the actual content of the footnote, as
	 opposed to a footnote marker. In this case, the target
	 specified by the HREF value, if any, is the footnote marker.

	 It has been suggested that the combination of REV=FOOTNOTE and
	 NAME=...  on an A element may be used to imply that the
	 enclosed content not be rendered until a link to it is
	 explicitly traversed, at which time it can be presented in a
	 popup window. This would allow for the inclusion of footnote
	 text within a document that would not be visible until the
	 reader wanted it to be presented. Developers of user agents are
	 free to experiment with  this proposed feature, but there is no
	 requirement that it be implemented.

      GLOSSARY
	 The GLOSSARY relationship identifies a glossary.

	 When REL=GLOSSARY, the target document is a glossary.  When
	 REV=GLOSSARY, the current document is a glossary.

	 If the hypertext link is specified with REL in a LINK element,
	 an HTML user agent may present an icon in a tool bar.

	 A glossary may be directly presented as an HTML document which
	 is organized and presented in a style reminiscent of a
	 paper-based glossary.

	 A glossary may also be accessed through an intermediary query
	 mechanism.  For example, the user highlights a word or phrase
	 and presses the glossary button, thereby accessing the linked
	 object and passing the highlighted text as an argument.  The
	 server returns the glossary entry relevant to the highlighted
	 word.

   4g. Meta Documents
      There are classes of information which are not intrinsic to a
      document, but for which a clear and unambiguous association is
      often useful or even necessary.  This section defines a small set
      of keywords which are related to ownership and legal notices.

      Any attempt to rigorously define a closed set of meta- data
      classes, types, and formats is doomed to failure, partly due to
      the  need for ongoing experimentation.  Hence, the META keyword
      may be used to identify meta documents which do not necesarily
      have a clear or unambiguous definition. The content of the target
      node may be as specific format as  a MARC record or an FGDC
      record, or it may be an author-defined format.
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      For each of the relationship keywords listed in this section, if
      the relationship is specified with REL in a LINK element, an HTML
      user agent may present a labeled icon in a tool bar.

      AUTHOR
	 The AUTHOR relationship identifies a hypertext link to
	 an author.

	 The hypertext link may be to the author's home page, a
	 biography, an audio or video clip, or an agent which sends mail
	 to the author (e.g., using the `mailto:' scheme).

      COPYRIGHT
	 The COPYRIGHT relationship identifies a hypertext link to a
	 copyright notice.

	 While it is arguable whether a copyright notice is required in
	 every HTML file to assert copyright protection on it, there is
	 clearly a desire to express copyright notice among a sufficient
	 portion of the user community to justify support.

	 A basic copyright notice for this document may simply state:
	 "Copyright 1995 by Murray C.  Maloney".  It may be desirable,
	 in place of or in addition to such a notice, to have a
	 hypertext link between each HTML document in a set and a single
	 copyright notice, as in the following examples:
	     <LINK REL=COPYRIGHT HREF="copyright.html">
	     <A REL=COPYRIGHT HREF="copyright.html">
	     Copyright 1995 by Murray C. Maloney</A>

      DISCLAIMER
	 The DISCLAIMER relationship identifies a hypertext link to a
	 legal disclaimer.  Usage is expected to be similar to that  of
	 the COPYRIGHT hypertext link. As with the copyright notice,
	 there is no intention or expectation that such a link would be
	 the only way to express a disclaimer.

      EDITOR
	 The EDITOR relationship identifies a hypertext link to an
	 editor. Usage is expected to be similar to that of the AUTHOR
	 hypertext link.

      META
	 The META relationship identifies a hypertext link to a node
	 which contains meta-information related to the  current
	 document. This is intended to be a generalized meta-data
	 relationship descriptor.

      PUBLISHER
	 The PUBLISHER relationship identifies a hypertext link to a
	 publisher.  Usage is expected to be similar to that of the
	 AUTHOR hypertext link.

      TRADEMARK
	 The TRADEMARK relationship identifies a hypertext link to a
	 trademark notice.  Usage is expected to be similar to that of
	 the COPYRIGHT hypertext link.
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   4f. Other REL and REV Values Under Discussion
      The POINTER keyword is an invention of the author.

      The BANNER, BOOKMARK, HOTLIST and STYLESHEET keywords are
      described in Dave Raggett's Internet Draft on HTML 3.0.  Recent
      discussions tend to indicate that these keywords may not be
      appropriate for use as REL/REV values.  Dave Raggett's further
      explanation and justification is needed before any further
      discussion or decision can be made as to the future status of
      these keywords.

      The LANG attribute is described in Dave Raggett's Internet Draft
      on HTML 3.0. It has been applied to various HTML elements, not
      including the LINK and A elements. The author suggests that LANG
      is a useful attribute to apply to the LINK and A elements.  See
      also the discussion of REL=TRANSLATION.

      BANNER
	 The BANNER relationship identifies a document banner.

	 When REL=BANNER, the target document is to be included  within
	 the current document as a banner. A banner is typically used
	 for corporate logos, custom toolbars, and other information
	 which  would not typically be scrolled with the body of a
	 document.

	 When REV=BANNER, the current document is a banner. This may be
	 used, in future, to provide error-checking or to prevent the
	 use of a document as a banner unless it has been explicitly
	 identified as a valid source. (Or not!  Sorry, I was reaching
	 for a useful meaning.)

	 Compelling arguments have been made against the need for  a
	 REL=BANNER value, which is simply a special case of the INCLUDE
	 mechanism.
      BOOKMARK
	 The BOOKMARK relationship identifies a bookmark.

	 Bookmarks are used to provide direct links to key entry points
	 into an extended document. The TITLE attribute may be used to
	 label the bookmark.  Several bookmarks may be defined in each
	 document, and provide a means for orienting users in extended
	 documents.

      HOTLIST
	 RESERVED: This keyword has been proposed by Dave Raggett. Its
	 meaning and purpose require further explanation.  A placeholder
	 is being maintained until such time as Dave has had an
	 opportunity to provide further explanation, examples,
	 discussion and justification.

	 If the hypertext link is specified with REL in a LINK element,
	 an HTML user agent may present an icon in a tool bar.

      LANG
	 The LANG attribute indicates the language of the target
	 document.
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	 The LANG attribute is optional and has no default value. It may
	 be used for purely informational purposes by an HTML user
	 agent, or by a robot for language classification.

	 Used in combinatiuon with a proposed REL=TRANSLATION and a
	 user's language preference setting, an HTML user agent may
	 intelligently select from a collection of otherwise equivalent
	 hypertext links expressed with the LINK element.  If the user's
	 language preference is not available, the user agent may
	 present a virtual menu of language options.

	 See the Internet Draft on the Internatiolisation of HTML for
	 a definition of the values of this attribute.

      POINTER
	 The pointer relationship identifies a hypertext pointer. That
	 is, this is a way to do indirection in HTML.

	 When REV=POINTER, the anchor is a pointer to the target
	 document. When a hypertext link is traversed to a LINK or A
	 element with REV=POINTER, the target specified by the HREF
	 value should be traversed, and so on, until a target without
	 REV=POINTER is retrieved.
	     <LINK NAME=PSEUDO REV=POINTER HREF="real.html">

	 When REL=POINTER, the target is a pointer to the real target.
	 This value can be used by a user agent to perform a pre-fetch
	 of the specified target for evaluation until the real target is
	 reached.

	 NOTE: The authors propose that the NAME attribute be removed
	 from the LINK element, or that a practical use for it should be
	 defined. For example, hypertext indirection can be specified by
	 providing both a NAME and an HREF value on the LINK element, in
	 combination with a specific REL or REV value, such as POINTER.
	 Some support exists among members of the HTML Working Group to
	 provide for hypertext indirection with the LINK element.  There
	 is no other reason for an author to define a target by using
	 the NAME attribute on a LINK element, since the resulting
	 target address is functionally equivalent to the address of the
	 document in which such a target is defined.

      STYLESHEET
	 The STYLESHEET relationship identifies a stylesheet.

	 When REL=STYLESHEET, the target document is a stylesheet. When
	 associated with a LINK element, the author/publisher is
	 expressing an expectation that the target stylesheet  will be
	 applied by the HTML user agent. When associated with an A
	 element, an HTML user agent may simply retrieve the target
	 stylesheet for display, or it may launch a stylesheet editor
	 with the target stylesheet.

	 When REV=STYLESHEET, the current document is a stylesheet and
	 the target document may be a demonstration of its use. In
	 general, it is not anticipated that stylesheets will contain
	 LINK or A elements, as they are not projected  to be HTML
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	 documents.

      TRANSLATION
	 The TRANSLATION relationship specifies a translation to
	 another language.

	 When REL=TRANSLATION, the target is a translation to another
	 language. This value will most typically be used with the LINK
	 element, in combination with specification of the target
	 document's language as a LANG attribute value.  Presumably,
	 REL=TRANSLATION can be used with the A element to specify a
	 translation of a document fragment, such as a  phrase in a
	 foreign language.

	 When REV=TRANSLATION, the current document, or document
	 fragment, is a translation of the target.

      URC
	 The URC relationship identifies a Uniform Resource Catalogue
	 for the current document.

	 This keyword has been proposed by Dave Raggett.  Its meaning
	 and purpose have not been explained to the author, but a
	 placeholder is being maintained until such time as Dave has had
	 an opportunity  provide explanation, examples,
	 discussion and justification.

5.  Hypertext Includes
   There have been many discussions in various forums which clearly
   indicate that hypertext includes are a desired feature of the HTML
   language, and for which widespread user agent support is needed.

   There are, apparently, three popular syntactic approaches to
   inclusion: specifying INCLUDE as REL value on the A and LINK
   elements, specifying a newly-defined and specially- purposed INCLUDE
   element (which would presumably also have REL and REV attributes),
   and using SGML entities.  Each is described and discussed below, but
   no arguments are presented.

   In either case,  there is an expectation that processing of an
   INCLUDE link would result in the INCLUDE value being deleted from the
   REL list and inserted into the REV list.  In other words, a
   REL=INCLUDE indicates that the inclusion has yet to happen, while a
   REV=INCLUDE indicates that the inclusion has already happened. It is
   helpful, for legal and copyright purposes, that included material be
   identifiable at all times.

   Note that the form of inclusion referred to here is also known as
   Transclusion, or as client side inclusion.  It may happen either
   automatically, when a document is loaded into an HTML client,
   or explicitly: for example when the user selects an icon, included
   text may appear at that point in the current document.

   5a. INCLUDE as a REL or REV Value
      INCLUDE relationship identifies a document for inclusion.

      When REL=INCLUDE, the target document should be included at the
      anchor location. This value is typically, though not always, used
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      with the A element.  Using this value on a LINK element implies
      that the included document only contains information which is
      valid within the HEAD of an HTML document.

      When REV=INCLUDE, the current document is identifying itself as an
      included document in the target document.

   5b. INCLUDE as an Element
      An anchor may also be specified  using a newly-defined INCLUDE
      element:
	  <INCLUDE REL=INCLUDE HREF="boilerplate.html"></INCLUDE>

      In this scheme, when the hypertext link is traversed, and the
      content of the target document is included, the INCLUDE element
      would surround the included text. As a function of traversing the
      link, the REL attribute value would be transformed to a REV value,
      thus maintaining information about the link.
          <INCLUDE REV=INCLUDE HREF="boilerplate.html">
          This is the boilerplate text
          </INCLUDE>

   5c. SGML external entitities
      SGML provides a mechanism for specifying external entities and
      including them, by reference, in an SGML document.

      Unfortunately, the current HTML browser technology cannot easily
      support the use of SGML entities, and they cannot be used in
      a way that is completely backwards-compatible with existing
      software.

6. Hypertext Paths
   NOTE: Recent discussions tend to indicate that the mechanisms and
   language uses needed to support paths have not been adequately
   articulated or specified. This section appears here for historical
   completeness. Dave Raggett's further explanation and justification is
   needed before any further discussion or decision can be made as to
   the future status of these keywords.

   Paths are described briefly in Dave Raggett's Internet Draft on HTML
   3.0, and reproduced below without further explanation. Further
   discussion, explanation and justification from Dave are clearly
   required before  any further public discussion or decision can be
   made as to the future status of these keywords.  The material below
   is reproduced for historic purposes and may be subject to future
   revision.

   Values for use in defining Guided Tours with <A> element.  These
   allow Guided Tours to be defined using HTML, for instance as part of
   tables of contents,  for example:
      <A REL=NODE REV=TOC HREF="Chap1.html">

   NODE
      The NODE relationship implies PREVIOUS/NEXT LINKs for given URI.

   PATH
      The PATH relationship specifies that the given URI contains <A
      REL=NODE> links that should be inserted into the guided tour.

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      The browser treats the REL=NODE URIs as forming a sequence of
      nodes to follow and sets the <LINK REL=PREVIOUS>, NEXT as
      appropriate for each node as it is visited.

7. Proposed New Attributes for A and LINK Elements

   Through the course of discussions, suggestions have been made to
   create new attributes for the LINK and/or A elements. These are
   preliminary discussions, with no sample implementations to
   demonstrate support.

   7a. ACTION or STYLE or PROCESS or PRESENT
      Activating a link in the HTML user agents of mid-1995 typically
      results in the linked object replacing the current object in the
      presentation window of the user agent. By convention, HTML user
      agents typically provide an alternate method which spawns another
      window and presents the linked object in it.

      It has been suggested by Ian Graham and Roy Fielding, and agreed
      upon by many others, that the author should have some means to
      indicate a preference for the manner in which the user agent
      should present the linked object to the user. As you can see, the
      name of the attribute still needs to be settled.

	 From Ian Graham: It seems reasonable to allow the
	 author to suggest browser behavior when links are activated.
	 For example,  when I click on a LINK button, should I clone a
	 window for the link, or pop up a subwindow for a glossary
	 entry?  Perhaps this should be part of a CLASS attribute, but
	 to my mind CLASS should be used to define the
	 presentation/meaning of a document element in the document BODY
	 as opposed to browser behavior.

	 And from Roy Fielding: Presentation semantics -- where should
	 the results be "placed".  A `STYLE=""' attribute (defined as
	 SGML NAMES) would do nicely here.

      Possible values and their meanings are:
      CLONE
	 Present the linked object in a presentation window which is a
	 clone of the current presentation window. That is popup another
	 persistent window.

	 See the Netscape Frames proposal for one way to do this, using
	 named windows and the TARGET attribute described below.

      EMBED
	 Present the linked object at the current location.  This
	 provides a syntax for expressing "stretch text", but it also
	 presents numerous problems.  This will be subject to much
	 debate.  See the section on Include, above.

      REPLACE
	 The default behavior.  Present the linked object in the current
	 presentation window, replacing the current object completely.

      POPUP
	 Present the linked object in a non-persistent presentation
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	 window.  That is, show the linked object while the user is
	 activating the link, and make it disappear when the user
	 releases activation. In the case that the popup is entered
	 without user activation, the user agent may provide a "Cancel"
	 button or another mechanism to make the popup window
	 disappear.

      SPLITSCREEN or HORSPLIT
	 Present the linked object in one pane of a horizontally split
	 window.

      ALONGSIDE or VERSPLIT
	 Present the linked object in one pane of a vertically split
	 window.

   7b. TARGET
      Netscape Corporation have proposed to add a TARGET attribute to
      the A element; its value is the name of the window in which to
      display the result of following the link.

      This is most useful in conjunction with a mechanism (such as
      FRAMES, not discussed in this document) to give names to windows.
      However, if no window exists with the given name, a reasonable
      action is to create such a window.

      An HTML client in a non-windowing environment would have to find
      some way to indicate the presence of multuple active document areas,
      and to allow navigation amongst them.

   7c. DINGBAT
      The DINGBAT attribute, applied to the LINK element and the A
      element, would be used to specify the entity name of a graphic
      image (an icon) to associate with a hypertext link. The DINGBAT
      attribute values must be specified by the HTML DTD as an SGML name
      token group.

      When used with LINK, the icon may be used on an HTML user agent
      toolbar. When used with A, the icon may be placed in close
      proximity to the anchor's highlighted text, as a footnote marker
      for example.

      There are advantages to using an entity rather than an external
      graphic.  Presumably, a user agent would pre-load the standard set
      of entities, thereby eliminating the need to fetch a graphic
      across the network. It is hoped that user agents will provide
      users with a means to specify the system location of personalized
      or customized versions of standard icons, thereby offering the
      user the opportunity to exercise greater control over the user
      interface and the graphical presentation.

      The DINGBAT attribute has already been proposed for lists and list
      items in Dave Raggett's Internet Draft on HTML 3.0.  User agent
      behavior, in the face of contention between DINGBAT and SRC, must
      be specified.

   7d. HILITE or HIGHLIGHT
      Roy Fielding has pointed out that the author can
      indicate a preference for the style of anchor
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      highlighting. So far, the list of candidate
      keywords are:
      * None
      * Button
      * IconOnly
      * Underline
      * Outline
      * Reverse

   7e. METHOD
      From Ian Graham: It would often be convenient to
      access a link using a defined HTTP method other than GET.  For
      example, suppose I have a LINK attribute defining a related,
      searchable glossary.  One desirable behavior is as follows: the
      user highlights a word and clicks a mouse button (or presses a
      glossary button). The browser accesses the linked object, passing
      to it the highlighted text.  The server then returns the glossary
      entry relevant to the highlighted word.  This requires
      standardised methods and data encoding schemes. There is only one,
      namely the HTTP TEXTSEARCH method, which is how ISINDEX search
      queries are sent to a server.  I therefore propose that the METHOD
      attribute have two possible values, namely GET|TEXTSEARCH, to
      indicate how the client should access the linked resource.

   7f. SRC
      The SRC attribute, applied to the LINK element and the A element,
      would be used to specify the location of a file containing a
      graphic image (an icon) to associate with a hypertext link. When
      used with LINK, the icon may be used on an HTML user agent
      toolbar. When used with A, the icon may be placed in close
      proximity to the anchor's highlighted text,  as in the case of a
      footnote marker for example.

      This extension of the applicability of the SRC attribute has
      already been proposed for lists, list items, and admonishments in
      Dave Raggett's Internet Draft on HTML 3.0.  User agent behavior
      remains to be specified in the face of contention between DINGBAT
      and SRC attributes.

   7g. WHEN
      Roy Fielding and Ian Graham have pointed out that user agents
      currently exhibit different behavior between their processing of
      hypertext links specified with the SRC attribute and those
      specifiewd with HREF. Typically, user agents await user activation
      before  traversing a hypertext link specified with an HREF
      attribute, while those specified with SRC are more often fetched
      immediately.  This distinction is a natural consequence of a
      design which uses the SRC attribute to specify a hypertext link to
      an embedded graphical image.

      The author can take advantage of an ability  to specify when, or
      the type of event, which should initiate the hypertext link.

      Roy Fielding suggested the following possible attribute values:
	 UserSelect   as is the case for anchors and FORMS
	 AutoEntry    as is the case for EMBED or IMG
	 AutoExit     an interesting derivative
	 Export       only used external to the user process
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      In response, Murray Maloney asked:  Would the AutoExit derivative
      provide a means for me to do indirection?  For example, in
      document A I have <A HREF=B#foo>, and in B I have <LINK NAME=foo
      STYLE=AutoExit HREF=C>.  Would asserting the anchor in A lead me
      to C?  If so, wonderful.  If not, then why not and what then?

      Please explain the meaning of "Export"?  That is, if I use it what
      does it imply about "when should the action take place"?

      (Liam Quin things Export doesn't imply any action at all, but
      doesn't yet understand why it might be useful)

      Consider these examples:
	  <LINK ACTION=POPUP WHEN=AutoEntry
	  REL=COPYRIGHT HREF="copyright.html">
	  <A ACTION=POPUP WHEN=AutoEntry
	  REL=COPYRIGHT HREF="copyright.html">
	  Copyright 1995 by Murray C. Maloney</A>
      In either case, the user agent is expected to display the target
      document in a popup as soon as the current document is retrieved.

   7h. OBSOLETES, UPDATES and DERIVED-FROM:
      Roy Fielding also suggested the following relations:
      OBSOLETES
	 when REL=OBSOLETES, the target document is a later version of
	 the current document; when REV=OBSOLETES, the target document
	 is obsoleted by the current document.

      UPDATES
	 When REL=UPDATES, the target document contains revisions to the
	 current document (would REVISES be clearer?).

      DERIVED-FROM
	 When REL=DERIVED-FROM, the target document was derived from the
	 current document; when REV=DERIVED-FROM, the current document
	 was derived from the target document, perhaps by automatic
	 processing or by manual editing.

8. Acknowledgements
   This paper is the synthesis and codification of ideas from
   a variety of sources.  It is only fitting that those who
   have contributed to the discussion in various forums should
   be acknowledged for their part in the recent attempt to
   move this work forward.
       Terry Allen, O'Reilly and Associates, terry@ora.com
       Murray M. Altheim, NTTC, murray.altheim@nttc.edu
       Brian Behlendorf, Indiana Univ., brian@organic.com
       Bert Bos, Rijksuniversiteit Groningen, bert@let.rug.nl
       Jon Bosak, Novell, Jon Bosak@novell.com
       Henry Budgett, SCO, henryb@sco.com
       Paul Burchard, burchard@geom.umn.edu
       Dan Connolly, MIT/W3C, connolly@w3.org
       Steve DeRose, Electronic Book Technologies, steve@ebt.com
       Joe English, joe@trystero.art.com
       Roy T. Fielding, Univ. of California (Irvine), fielding@ics.uci.edu
       Peter Flynn, pflynn@curia.ucc.ie
       Ian Graham, Univ. of Toronto, igraham@utirc.utoronto.ca
Murray & Quin                                                  [Page 23]

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       Dave Hollander, HP, dmh@hpsgml.fc.hp.com
       Alex Hopmann, ResNova Software, Inc., hopmann@holonet.net
       Craig Hubley, Craig Hubley & Associates, craig@passport.ca
       Albert Lunde, Albert-Lunde@nwu.edu
       Tom Magliery, NCSA, mag@ncsa.uiuc.edu
       Eve Maler, ArborText, eve@doctools.com
       Larry Masinter, Xerox, masinter@parc.xerox.com
       Eric Miller, OCLC, emiller@oclc.org
       Lou Montulli, Netscape Communications, montulli@netscape.com
       David Morris, dwm@shell.portal.com
       Dave Raggett, MIT/W3C, dsr@w3.org
       Bob Stayton, SCO, bobs@sco.com
       Stu Weibel, OCLC, weibel@oclc.org
       Faith Zack, SCO, faithz@sco.com


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