If anyone cares a draft data model is visible at:
http://webpages.charter.net/thecomputercollection/misc/manualmodel.pdf
(It may change as I work on the design).
Biggest change from earlier discussions: I found no reason not to merge
the manuals/artifacts relationship table into the artifact table, and I
reduced the primary key columns down to only those absolutely necessary
to guarantee uniqueness.
JRJ