XML Catalog entries for docbook-xml

[Jor-el <jorel@austin.rr.com>]

Hi,

	The docbook-xml package bundles the dtd's from four different
versions - 4.2, 4.1, 4.0 and 3.1.7 . The public id strings of the DTDs are
very similar. Here are two examples :

dbhierx.mod from 4.0 : 
	"-//Norman Walsh//ENTITIES DocBk XML Document Hierarchy V4.0//EN"
dbhierx.mod from 4.1 :
	"-//Norman Walsh//ENTITIES DocBk XML Document Hierarchy
V4.1.2//EN"

	Since the public ids are _almost_ the same, delegating the lookups
to a second level catalog from the root catalog isnt very efficient
(though its technically feasible). 

	Here is another problem :

soextblx.dtd from 4.2.cr1 :
	"-//OASIS/DTD XML Exchange Table Model 19990315//EN"
soextblx.dtd from 4.1 :
	"-//OASIS/DTD XML Exchange Table Model 19990315//EN"

	There is no point in having two versions of the same file if there
is no way the catalog heirarchy can distinguish between the two. The only
scenario this would be useful in is when one pointed directly to the
catalog servicing the specific version of the DTDs one is
interested in (bypassing the catalog chain). OTOH, the root catalog has to
point to a specific version of the DTDs (the latest seems the most
logical) or else the catalog chain will never be able to point to these
files.

	So here is what I propose : the root catalog chain will only point
to the most recent versions of DTDs when a package provides multiple
versions. If this is not reasonable, please let me know at the earliest.

Thanks,
Jor-el