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   Re: [xml-dev] entity definitions

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On Mon, Apr 26, 2004 at 10:45:03AM +0100, David Carlisle wrote:
>There only seem to be examples of entity definition, none of entity

The last example contains references.  But the purpose isn't to change
references, only to change definitions/declarations.

>The thing that has killed all previous attempts to do this is that in
>XML 1.0 (and 1.1) a reference to "& e a c u t e ;" results in a
>non-wellformed document unless there is also a <!DOCTYPE and if you are
>going to have a doctype declaration, you may as well define the entity
>in dtd syntax.

This proposal is intended to modify XML 1.0 by changing parts of section
4.1, specifically creating an alternative mechanism to fulfill the Entity
Declared WF/V Constraint.  I have probably not made this sufficiently clear,
so I will provide text to update that section, allowing this alternate

>There was a request at XML 1.1 to make an undefined entity (that is,
>undefined by dtd) a validity rather than WF error, exactly to allow this
>kind of alternative syntax, but it wasn't accepted.

Well, it's already possible, if you're not validating and standalone="no".

Quoting from the final sentence of Well-Formedness Constraint: Entity
Declared in section 4.1 of XML 1.0:

"Note that if entities are declared in the external subset or in external
parameter entities, a non-validating processor is not obligated to read and
process their declarations; for such documents, the rule that an entity must
be declared is a well-formedness constraint only if standalone='yes'."

By definition, all entities declared via EDML are either external or part of
the "external subset" (albeit for schema languages other than DTD).

The first clause of the same paragraph, "In a document without any DTD" is
problematic, potentially.  *shrug*

Bob Foster also suggested, in email, that it might be possible to use XSLT
to perform a transformation (pick up the entity and entities PIs, and stick
them in the external subset).  I may need to ask on xsl-list, but I don't
think that this is possible.  On the other hand, it might be possible to
generate an internal subset.  But it isn't clear that the processor feeding
the XSLT engine would leave the entities unexpanded (the general XSLT advice
seems to be: you can't ever see an entity).  So I need to ask some experts
on xsl-list, but I'm doubtful whether there's an XSLT solution for

I'm currently investigating what it would take to make a generic SAX filter
that would effectively act as a macro processor (this only handles the
processing instruction in instance document case, though; the use of entity
definitions in schema documents isn't addressed).

Amelia A. Lewis                    amyzing {at} talsever.com
Igne natura renovatur integra.


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