The current DTD (dated 1994/09/26 16:10:19) says:
<!ENTITY % linkType "NAME"
-- a list of these will be specified at a later date -->
<!ENTITY % linkExtraAttributes
"REL %linkType #IMPLIED -- forward relationship type --
REV %linkType #IMPLIED -- reversed relationship type
to referent data --
URN CDATA #IMPLIED -- universal resource number --
TITLE CDATA #IMPLIED -- advisory only --
METHODS NAMES #IMPLIED -- supported public methods of the object:
TEXTSEARCH, GET, HEAD, ... --
">
So REL/REV are standard attributes whose values are constrained
to the syntax of an SGML name (i.e. /[A-Za-z][A-Za-z0-9\.\-]*/),
but there is no standard set of values (like PARENT, PRECEDES,
STYLESHEET, OWNER, REPLY-TO).
I guess that's a fairly accurate description of the current state of
affairs. We should probably discuss the future plans for REL/REV a
little bit to be sure that this discription is consistent with the
future plans.
For example, I'd like for browsers to have standard up/next/previous/top
buttons outside the HTML text area. A document might say:
<head>
<link rel="parent" href="../index.html">
<link rel="next" href="section_4.html">
<link rev="next" href="section_2.html">
</head>
<body>
<h1>animals</h1>
<ol>
<li> <a rel="child" href="section_3/part_1.html">Frogs</a>
<li> <a rel="child" href="section_3/part_2.html">Dogs</a>
<li> <a rel="child" href="section_3/part_3.html">Cats</a>
</ol>
This would tell the browser where to link its next/previous/up
buttons. Plus, it would allow tools to be built to walk a tree of
parent/child documents and, for example, print out the aggregate, or
display a graphical map or table of contents.
So I don't know what prose to put in the spec, but I think REL/REV
are standard attributes at this point.
I think.
Dan