[xml] alternate DTD locations

[Paul Emberson <lists calidasoft co uk>]

Hi,

Is is possible to specify a search path for external entities when using 
the xmlreader interface?

Alternatively, is it possible to specify a DTD to fall back on if the 
one specified in the XML file isn't found (again with xmlreader).  E.g. 
it is possible to set a schema with xmlTextReaderSetSchema but I don't 
see a DTD equivalent.

Background:

I am working on a tool which takes its input from xml files which 
specify a dtd in the system identifier.  Currently I have to make 
several copies of the DTDs into whichever directory the input is being 
read from.  I want to be able to specify where the DTDs are stored as a 
configuration option, or possibly derive it from where the executable 
has been installed.  Ideally, I want to be able to specify something 
like an include directory which acts as a base for the URIs in the 
system identifier.

Thanks for any help or suggestions,

Paul