Re: And the DTD says, "I'm NOT dead yet!!"

[Norman Walsh <ndw@nwalsh.com>]

/ Bob Kline <bkline@rksystems.com> was heard to say:
[...]
| don't think this is one of them.  The most common uses I have seen for
| entities are:
| 
|   1. to create macros for commonly used content-model groups; and
|   2. to create a kludge for working around the lack of support for
|      namespaces in DTDs.
| 
| The first is handled fairly well by named groups (<xsd:group name=...)
| and the second problem doesn't exist because XML Schema supports
| namespaces.  External entities in DTDs correspond pretty well to the
| <xsd:include ...> element in XML Schema.

The significant feature that seems to be missing, but might be addressed
with <redefine> if it's extended to allow complete redefinition of
model groups and attribute groups (i.e., redefinition without reference
to the original), is the ability to change the groups in derived schemas.

Suppose I have the following PE in my DTD:

  <!ENTITY % article.content "para|note|warning">

I can easily construct a derived DTD that does not allow warnings:

  <!ENTITY % original.dtd SYSTEM "...">
  <!ENTITY % article.content "para|note">
  %original.dtd;

It's not clear that I can do this with XML Schemas, and I do this *a lot*.

                                        Be seeing you,
                                          norm

-- 
Norman.Walsh@East.Sun.COM | There has never been a perfect government,
XML Technology Center     | because men have passions; and if they did
Sun Microsystems, Inc.    | not have passions, there would be no need
                          | for government.--Voltaire