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

At 4:44 PM -0600 10/29/01, Bullard, Claude L (Len) wrote:

>Yes, I've seen problems with not knowing something is an ID but 
>the answer has been, find the Schema or DTD?  What, no schema 
>or DTD?  Then why do you care?  Well I need to know if these 
>are unique?  Isn't that a processor issue of local scope? Yes. 

No, you've wandered off the point here. That's not really why we care. We care because we're trying to link to named things. The uniqueness comes out of the need to link to something, but more than anything else what we need is the way to link to it. It would not be a disaster if instead of xml:id we had a potentially non-unique xml:name that could still be linked to. As is the case with XPath based XPointers, such a link might point to multiple discontiguous nodes. So there are good reasons to want xml:name/xml:id to have a unique value within a document.

Nonetheless uniqueness alone is not driving this discussion. The use-case that calls out for this is, as Tim Bray has pointed out, linking to elements in a manner that is most likely to survive document edits. This requires the ability to attach linkable names to elements. And we can certainly care about this when there's no DTD or schema in sight. 

| Elliotte Rusty Harold | elharo@metalab.unc.edu | Writer/Programmer |
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