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Elliotte Harold wrote:
> I don't know about W3C schemas, but the XML spec is not at all clear
> that a non-deterministic content model in a DTD is an error. Indeed some
> versions of Xerces have not so flagged it.
It's actually pretty clear. Section 3.2.1 says "For compatibility, it is
an error if the content model allows an element to match more than one
occurrence of an element type in the content model." The phrase "for
compatibility" doesn't weaken the constraint; it's an error.
The later reference to the non-normative section E doesn't weaken the
constraint, either. Whatever section E says, it's non-normative.
Many processors over time haven't flagged non-deterministic models as
errors or haven't done so correctly, either because it's a lot easier
not to check or the authors didn't like the constraint. Many people
don't like the constraint. That doesn't mean it isn't an error.
> Section E of the spec is classified as non-normative, and even that only
> says "XML processors built using SGML systems may flag non-deterministic
> content models as errors." It does not say they are required to do so.
> And what about XML processors not built on top of SGML systems?
What about 'em?