Re: DOCBOOK: Linking in DocBook (specifically for EBNF, but more generally as well)

[Norman Walsh <ndw at nwalsh dot com>]

/ Terry Allen <tallen@sonic.net> was heard to say:
| me that something else won't come along.  But to stick to the point, has 
| Xpath been implemented, and how completely?  (That is, how do we know
| it solves its problem completely?)

Given the number of XSLT processors available, I think it's safe
to say that XPath has been implemented several times.

| | that support XPointer yet in fragment identifiers on URIs, but that's not 
| | surprising.  I know of some internal use of the #foo shortcut, where a 
| | trivial transform is done to turn it into a classic IDREF.
| 
| In HTML variants, is it required that NAME atts have values unique
| within the instance (I haven't kept up with XHTML; the HTML 4.0
| DTD doesn't require it)?  (That is, how close to ID/IDREF are we
| getting?)

Keep in mind that fragment identifiers for HTML (an SGML
application) and XML are different. The #foo and id('foo')
XPointer components, when pointing into an XML document, point
to IDs (i.e., XML ID-valued attributes), not NAME atts on any
specific element.

| It would seem we're close; it's unfortunate we can't wait longer
| for the present purpose.

No one said we can't, exactly. At most, I've said I'd like not
to have to. :-)

| What worries me here is that we're dipping our toe into the linking
| problem without considering a thoroughgoing change across the DTD, and
| without tool support.  We were more conservative in the past.

Good point. To play devils advocate, I'll point out that we're
discussing this problem in the context of an element with such
extensive processing expectations that tools support would be an
issue even without the linking question.

But the fact that '#foo' won't work in existing tools, even for
ID/IDREF-type links, is a cause for much concern...

| I can see that for linking to nonterminal definitions there should be 
| only one target to point at, so it would seem safe to go the Xpointer
| route; would we use the same approach to convert all present
| ID/IDREF (not ID/IDREFS) links?

I'm certainly not proposing that yet. Not before widespread
tools support, anyway. As you said, we've waited five years to
address the general linking issues, I think we can wait a couple
more.

| On second thought, maybe I'd prefer two attributes, too.

Yeah, I think so.

                                        Be seeing you,
                                          norm

-- 
Norman Walsh <ndw@nwalsh.com>      | It is seldom that any liberty is
http://www.oasis-open.org/docbook/ | lost all at once.--David Hume
Chair, DocBook Technical Committee |