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Re: [xml-dev] IDs considered harmful or why keys might be better thanIDs...

Ok I stand corrected. Internal subsets are easy to use and well supported as
you and john cowan, michael kay and others say.

So why do we need _another_ mechanism to declare IDs?

Jonathan (starting to wonder what this whole discussion is about ...)

David Brownell wrote:

> > > > The only reason that I see the need for something really lightweight
> > > > like
> > > > "xml:id" is that internal subsets are not well handled by common
> > > > software (e.g. SAX),
> Not at all true.
> > > Actually, SAX is able to report the types of attributes.  There is
> > > nothing in XML 1.0 requiring XML processors to make this information
> > > available, however.
> >
> > By "not well handled" I mean statements like this from the javadoc for
> > DeclHandler:
> >
> > "This is an optional extension handler for SAX2  ...
> But it's not the primary way to report whether an attribute is of
> type "ID".  When something in the internal subset is declared to
> be of type ID, then Attributes.getType() reports "ID" for that
> attribute, reported by startElement().  Those are non-optional
> parts of SAX.  (And the SAX1 analogue was non-optional too.)
> DeclHandler is used to report the DTD declarations.  You need
> it to see what attributes are #IMPLIED and omitted from instances,
> or to construct models of DTDs, or to see the exact constraints that
> apply to enumerated attributes.  You don't need it to see whether
> a given attribute is of type ID.
> - Dave
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