Re: [xml-dev] Re: determining ID-ness in XML

[David Brownell <david-b@pacbell.net>]

Not that I much like the solution of using PIs for this case, but
I'll speak up for them as a general tool.


> > No; but then I never understood why the use of processing instructions
> > had become infra dig. W3C politics, I hear whispered. Anyone care to share?
> 
> 1) They're not scoped, everything else about the language is.

Of course, not all problems require scoping ... clearly, not all
solutions should require it.  (Beyond "this document", or "this
location in the document", that is.)


> 2) They're not declared in the grammar (DTD/Schema), so their usage is not
> subject to any declarative/universal quality control: you're back to
> writing ad-hoc code in every application to check they occur where and 
> how they're supposed to.

Depends what kind of "usage" you're looking at.  One can associate
PI target names with notations, using DTDs, and (as was pointed out)
Schematron supports even more.. And "xml-*" names are more or less
global.  As has been pointed out, there's some circular logic lurking...
some folk dislike PIs, so support became scarce, so people couldn't
use them, then those same folk argued "no users, no more support".

But it would certainly have been healthier if the namespaces spec
hadn't precluded PI target names from having colons.  At any point
inside a document element, a QName used as a PI target name is
clearly going to be associated with at most one namespace ...

- Dave