Comment on DITA 1.1: Defining and using normative URIs for all DITA-Supplied Schema Components

["Grosso, Paul" <pgrosso@ptc.com>]

[EricS, Eliot, and I have been discussing this topic that
I am now putting forward as a comment on DITA 1.1.  paul]


All the DITA 1.1 DTD modules have official formal public
identifiers that are used to reference them.  For example,
topic.dtd references programmingDomain.ent via:

<!ENTITY % pr-d-dec     PUBLIC 
"-//OASIS//ENTITIES DITA Programming Domain//EN" 
"programmingDomain.ent"                        >
%pr-d-dec;

The public identifier can be used in a catalog to point to
wherever the desired module may really be.

However, the DITA 1.1 XSDs do not parallel this situation.
We have only defined URIs for the top level shells, and the
XSDs have xs:includes that refer directly to modules; e.g.,
topic.xsd references programmingDomain.xsd via:

  <xs:include schemaLocation="programmingDomain.xsd"/>

While it is true that one can put in a catalog entry to map
the URI "programmingDomain.xsd" to something, this tends to
be confusing to users, and the lack of more "official" URIs
for the modules doesn't seem to parallel the DTD situation.
It makes is harder for users who need to remap the URIs to 
another location for their purposes.

We should do for XSDs something similar to the DTDs.  We should
define normative OASIS URIs for each schema-related file in
the distribution, the xs:imports and xs:includes in all the
files should use these normative URIs, and the distributed 
catalogs should have entries that map these URIs appropriately.

This shouldn't change anything user-visible except for those
advanced users who are already trying to remap URIs via
catalog entries.  I think we should do this in 1.1.

paul