USE CASE OPR

a) PR needs some specific bookkeeping, to maintain an history of the data
production and help the control system doing its job. This is probably
some subset of the current PR bookkeeping information. This should be
designed as a subsystem of the main bookkeeping project, as its only user
will be the PR production system, and possibly some QA tools.

b) PR Production is done at different sites. This raises synchronization
issues between sites. A realtime sync is not needed, but a robust
infrastructure to transparently sync site-local bk databases to a central
one is needed.

c) the PR control system is written in OO perl, so an OO perl interface to
the bookkeeping system will be optimal.

d) PR will write to the event store. This makes important to define an API
to the evs before starting to design the PR bookkeeping.