Re: More comments on the HTML 3.0 draft

Bert Bos (
Tue, 25 Apr 95 08:24:11 EDT

Paul Burchard <> writes:

|Bert Bos <> writes:
|> p.18 "LINK":
|> I still don't see why we need both REL and REV. They have
|> exactly the same meaning.
|(I assume you meant, exactly the _opposite_ meaning.)

No, I mean the *same*.

|That's the point. Since links have two ends, it's inherent in the
|design that you want to be able to express reverse relationships.
|Given both REL and REV, the reversal can be accomplished precisely.
|(E.g., <A REV="Next"> to roll back history.)

Both REL and REV assign a type to a unidirectional hyperlink. They say
that the target fulfills role X relative to this document, where X is
parent, successor, glossary, translation, whatever. The choice of REL
or REV depends only on whether you can invent a name for the

"that is a (the) X of this" "this is a (the) X of that"
REL=parent is equivalent to REV=child
REL=successor is equivalent to REV=predecessor
REL=glossary is equivalent to REV=doc_for_which_that_is_glossary
REL=toc is equivalent to REV=doc_for_which_that_is_toc
REL=author is equivalent to REV=product

Sometimes you may want a verb instead of a noun (REV=made). Note that
values for REV are rather unintuitive. In fact REL is somewhat
ambiguous as well. Why not drop both and use ROLE instead (or maybe
even CLASS)?

|But given only REL, one would be forced to rely on an ad-hoc
|catalog of "reverse words" (parent/child, made/maker, next/back,
|etc). Beyond some dictionary of registered antonyms, there would be
|no reliable way to reverse relationships.

The "reverse relation" is still the *same* relation. Unless you want
to write a natural language generator, why would you want to find
English words for it? There is only one relationship, whether you call
it "parent", "child", "foo", or "R7547". If you want to express two
independent relations, you should use two LINKs instead of one LINK
with two attributes.


                          Bert Bos                      Alfa-informatica
                 <>           Rijksuniversiteit Groningen
    <>     Postbus 716, NL-9700 AS GRONINGEN