I can only comment on CA laws, but unregistered vehicles (or vehicles that ARE registered, but expired over 6 months) can be cited while parked on public property or parking lots with public access (your local grocery store or mall). And if they want to, instead of a citation, the vehicle can be impounded until registration is paid.
As for your citation, based on the sequence of numbers, it seems more like a local municipal code violation, but I could be wrong.