There are some some test material in the xmlarch.py distribution, but no
general introduction to XML/SGML architectures. There are some references
to resources at the xmlarch homepage (
http://www.infotek.no/~grove/software/xmlarch/xmlarch.html ) though.
I would like to point you to David Megginson's excellent XAF page. There
you will find introductions for both document designers and software
developers. See: http://www.megginson.com/XAF/index.html
Eliot Kimber has also written an introduction called 'A Tutorial
Introduction to SGML Architectures':
http://www.isogen.com/papers/archintro.html
See also The SGML/XML Web Page's links on 'Architectural Forms and SGML/XML
Architectures': http://www.sil.org/sgml/topics.html#archForms
For more formal descriptions see the Architectural Form Definition
Requirements [AFDR]:
http://www.ornl.gov/sgml/wg8/docs/n1920/html/clause-A.3.html and
Geir O.