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

[Marcus Carr <mrc@allette.com.au>]

[I can't post to ietf-xml-mime@imc.org, so have left them off.]

"Bullard, Claude L (Len)" wrote:

> What we got instead was a
> step by step inching into a system in which semantics
> are being inserted via magic strings that are eroding
> the boundary between processor and content.

It's true that that boundary has never been well defined, but the problem
predates XML - the same thing occurred daily in SGML. How many times did
you have to change ID to CDATA in a DTD because you wanted to parse a
single chapter of a defense document and didn't want to be inundated with
meaningless errors about dangling IDREFs? The fact is, the decision as to
whether a particular attribute value should be checked for uniqueness
depends on the scope or extent of the process - same as it ever was...

The DTD is suppposed to be the contract, yet for the reasons described
above, it was (and probably still is) common practice to declare attributes
as CDATA and then check their uniqueness during processing. This not only
removes the semantics from the DTD, it also completely removes them from
the instance, leaving them entirely in the processing application. A "magic
string" in the instance seems like a much better option than not storing
the information anywhere. In fact, given the choice, I'd probably prefer a
"magic string" over defining something as an ID in the DTD, since that
codifies semantics that so commonly don't fit with the current
requirements.


--
Regards,

Marcus Carr                      email:  mrc@allette.com.au
___________________________________________________________________
Allette Systems (Australia)      www:    http://www.allette.com.au
___________________________________________________________________
"Everything should be made as simple as possible, but not simpler."
       - Einstein