I've just managed to get RXP to use an XML catalog. I haven't done it tidily yet, but it's useful for validating XHTML without waiting for rxp to download the DTD each time.
Catalog support is only in the ‘test’ version of RXP, which I had to turn into a Debian package. I'll put the package somewhere sensible soon, although I expect the updated version will go into Debian eventually. There seems to be a new library called ‘libcatalog’, but I haven't really looked into it.
I bodged together a catalog file based on the example in the draft XML catalog specification, which points the public identifier for XHTML1 Transitional at a DTD installed by the ‘sgml-base’ Debian package. That package seems to provide SGML catalogs, but not XML ones, which look like they come in a more sensible format to me. Here's my little catalog:
<!DOCTYPE catalog PUBLIC "-//OASIS//DTD XML Catalogs V1.0//EN" "http://www.oasis-open.org/committees/entity/release/1.0/catalog.dtd"> <catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog" prefer="public"> <group xml:base="file:///usr/share/sgml/html/"> <public publicId="-//W3C//DTD XHTML 1.0 Transitional//EN" uri="dtd/xml/1.0/xhtml1-transitional.dtd" /> </group> </catalog>
I then had to set the XML_CATALOG_FILES environment variable
to it's filename, and then it worked!