There are certainly cases where an entity is useful for a class of
documents, but generally if an entity is of interest to more than one
document, it's also of interest to more than one class of documents:
for instance, the ISO character entity sets. I think the problem of
defining entity replacements is fundamentally different from defining
element structures, and should be addressed separately. Now,
certainly a class of documents could be defined by a combination of
element structure restrictions and an initial set of defined entities,
but the two things should not be conflated as DTDs conflate them.
> No, not at all. There is no XSchema equivalent of parameter
> entities.
That's unfortunate. We tried to kill them in XML, but couldn't
because they're so useful. The processing concerns they introduced in
XML go away if you treat them as ID'd objects and references thereto,
so there's no reason to avoid them and very good reasons to include
them. Especially since the syntax is going to be more verbose, the
gain in reusing pieces is larger.
-Chris
-- <!NOTATION SGML.Geek PUBLIC "-//Anonymous//NOTATION SGML Geek//EN"> <!ENTITY crism PUBLIC "-//O'Reilly//NONSGML Christopher R. Maden//EN" "<URL>http://www.oreilly.com/people/staff/crism/ <TEL>+1.617.499.7487 <USMAIL>90 Sherman Street, Cambridge, MA 02140 USA" NDATA SGML.Geek>