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Hi Rob, > The reason for this dichotomy is that XML processors are not required to > analyse the content model to see if it is deterministic *unless* the > instance document contains an element of that type. This is my > understanding of xml 1.0, 3.2.1 [1] which reads:- > > "For compatibility, it is an error if an element in the document can match > more than one occurrence of an element type in the content model." > > So, it is only an error if there is an element in the document!? In the > case of ibm47v01, there is not a "child4" element, so it is my understanding > that the processor does not need to build the DFA for its content model. Yes. Thanks for that. Interesting that I read that sentence many times and was still confused in this instance. Can't see the woods for the trees sometimes... <g> > Our XML Validator used to check every content model to see if it was > deterministic. However we changed this when we realised the impact it could > have on perform when processing very large DTDs. Normal Walsh's DocBook DTD > [2] is a good example of a DTD containing many element types, many of which > are not used by individual instance documents. I am still trying to get my head around how I would even approach checking for non-determinism. And I'm unsure whether what you've just told me will actually make it easier or harder to implement - irrespective of the relative processing efficiencies. cheers, gary
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