Re: DTDs and namespaces (was: using namespaces to version)

[Wayne Steele <xmlmaster@hotmail.com>]

One could, if one wanted, define an extension mechanism to allow for 
different kinds of processors to interpret DTDs differently, and yet 
faithfully preserve the meaning and syntax of DTDs as per XML 1.0.

This still won't support the "Full Generality" of namespace constructs in 
the instance documents, except for processors that buy into the appropriate 
extension mechanism. But it could allow for the same DTD to be useful to XML 
1.0 spec-as-written processors.

I despair of anyone getting excited enough to implement this, but it would 
work like this:

<?DTD-EX
   http://example.int/namespace.extension.for.dtds
   <!ENTITY % legacy   "IGNORE" >
   <!ENTITY % ns_aware "INCLUDE" >
?>

<!ENTITY % legacy   "INCLUDE" >
<!ENTITY % ns-aware "IGNORE" >

<![%legacy;[
   <!-- let's use the parameter entity trick -->
   <!-- introduced in the DTD for XML Schema -->
   <!ENTITY % prefix_a 'a:' >
   <!ENTITY % suffix_a ':a' >
   <!ENTITY % a        '%prefix_a;a' >
   <!ENTITY % a_nsdecl 'xmlns%suffix_a;' >

   <!ELEMENT %a; (#PCDATA)* >
   <!ATTLIST %a; %a_nsdecl; CDATA #IMPLIED >
]]>

<![%ns-aware;[
   <?xmlns prefix="A" uri="uri:foobar" ?>
   <!ELEMENT A:x (#PCDATA)* >
   <!-- since we know all about namespaces -->
   <!-- there's no need to declare the xmlns:* attribute -->
]]>

-Wayne Steele





>From: "C. M. Sperberg-McQueen" <cmsmcq@acm.org>
>
>In sum, we appear to be in emphatic agreement.  If one is willing to
>change the rules for interpreting DTDs and validating documents
>against them, one can use DTD notation to define sets of documents
>which use namespaces. ... Otherwise, only with restrictions
>on the use of namespace prefixes ...  C. M. Sperberg-McQueen
>
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