Validating IDREFS...

Lars Marius Garshol larsga at
Sat Sep 5 13:13:15 BST 1998

* Michael Kay
| * A dangling IDREF is an error; a dangling XPointer is not

They are both errors, but at different levels, which IMHO makes
perfect sense. To check your XPointers you have to run an XPointer
checker, since XPointer is not part of XML (and IMHO shouldn't be).

| That is what I mean by saying the two facilities are
| incompatible. Or to put it another way, once I have made a design
| choice to use IDREF or to use XPointer for the links in my
| documents, I am stuck with my choice.

Definitely not. As Lisa Rein points out it's easy to convert from
IDREFs to XPointers. Going the other way may not be possible, since
XPointer can do much that IDREFs cannot, in which case I guess that's
not what you want anyway. :)
| This is one of several situations in the XML family of standards
| where there is more than one way of doing the same thing, and no
| obvious way to choose between them. 

I've never felt that this was a difficult choice. For links inside the
document where you can count on IDs to be present, use IDREF, for
external links, links to arbitrary elements (or with even finer
granularity if required) use XPointer.

"These are, as I began, cumbersome ways / to kill a man. Simpler, direct, 
and much more neat / is to see that he is living somewhere in the middle /
of the twentieth century, and leave him there."     -- Edwin Brock

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