I've made a comps.dtd (attached) that validates the RHL 9 comps.xml using xmlproc_val, and which (to the best of my ability) expresses the logic in /usr/lib/python2.2/site-packages/rhpl/comps.py. I only started learning XML yesterday evening, so there may be problems.
I'm not sure what the dtd is useful for except validating. :) But as for validity (as opposed to well-formedness), the only thing that appears to really matter for comps.xml is whether comps.py can parse it. Which of course it can.
Note that comps.py has some requirements that the comps.dtd doesn't specify (e.g. that there must be a name for each group). I would specify this requirement, but I only know how to do that by specifying a child order in the dtd. comps.xml has groups with children in different orders. I don't know how to specify in the dtd "this child must exist exactly once, but it can appear as any child".
Note also that I included "requires" as a possible child for group. comps.py says this isn't in use any more, but it does parse it.
And finally, I see that the element metapkg is only used in the RHL 9 comps.xml in one place:
<group> <id>editors</id> <name>Editors</name> ... <grouplist> <groupreq>base</groupreq> <metapkg type="default">emacs</metapkg> <metapkg type="optional">xemacs</metapkg> </grouplist> <packagelist> <packagereq type="default">vim-enhanced</packagereq> <packagereq type="optional">vim-X11</packagereq> </packagelist> </group>
Looking through the anaconda code didn't help me figure it out quickly, and I didn't find anything useful on the web, so let me ask: what is a metapackage?
David