Re: Associating schema with document

[Murata Makoto <mura034@attglobal.net>]

> > However, if I
> > care compatibility, I still prefer to embed internal DTD subsets rather
> > than a PI or attribute.  Does use of PIs or attributes have any
> > advantages  over use of internal subsets?
> 
> Internal subsets don't support namespaces properly.

Since we are talking about COMPATIBILITY with or migration from DTDs, proper  
support of namespaces is irrelevant.

> Internal subsets can be quite unwieldly if you have large DTDs 
> (particularly if you have small instances).  
... 
> There's also a fundamental difference: instead of having the schema in one 
> place and referencing it, you are duplicating the schema information in 
> multiple places.  ...

These points are correct, but can be easily avoided by creating external parameter 
entities containing default values and ID/IDREF declarations and referencing such 
external parameter entites from internal subsets.  A disadvantage of this approach 
is that conformant processors do not necessarily read external parameter entities.  
However, this approach does not require RELAXNG-aware processors.

Cheers,

Makoto