Re: Relationship types

bosak@atlantic-83.Eng.Sun.COM (Jon Bosak) writes:
>While discussion continues on the issues raised by Eliot's post, allow
>me to pose a parallel but simpler set of questions.
>Assume that some syntax has been specified for labeling the
>relationship between link ends.  Consider the following incomplete
>list of relationship types, lifted directly from existing proposals
>for HTML standardization:
>   NEXT
>Is it possible to agree on a basic list of such types?

In English, possibly. Not much use for the rest of the world unless you as
a non-English speaker don't mind learning the meanings of some rather
complicated relationships in a foreign language.

>Is it useful to agree on a basic list of such types?

Not if you require a CHILD or NEXT behavior that doesn't match the guy in
the next cubicle's CHILD or NEXT. Not if you can't guarantee that XML
implementations will interoperably support the entire list.

To see how far we might have to go in creating that list, we could look to
an example of an attempt at encompassing the gamut of link types in Lee and
Murray Maloney's HTML draft (to which I believe you were alluding). Quite a
way it seems.

>If such a list were defined, would it be better to restrict the labels
>that could be applied to a relationship to the choices on the list, or
>would it be better to allow additional labels not on the list to be
>applied on an ad hoc basis?

We know how far the linktypes draft got on the Web. Why? Possibly because
it was both too restricting and too extensive -- you can't win it seems.
Developers had to choose either the complete set or a subset, so for
authors there was no common understanding of which were supported across
popular implementations, and therefore no guarantee of interoperability,
eg. it's dangerous to rely on <LINK REL=TOC> if only NCSA Mosaic supports

I didn't think XML was about restriction -- it's supposed to be a
meta-language, right? Wouldn't a restricted list mark the beginning of a
design stagnancy?


    Murray Altheim, Program Manager
    Spyglass, Inc., Cambridge, Massachusetts
    email: <mailto:murray@spyglass.com>
    http:  <http://www.cm.spyglass.com/murray/murray.html>
           "Give a monkey the tools and he'll eventually build a typewriter."