The masks are separate from, but must remain synchronised with, the data. It seems natural to store the masks in titles banks, use MTT to provide synchronisation and the database to distribute them. There is a snag though, minor time disordering means that time validities cannot exactly synchronise with run boundaries and this leads to complications when trying to efficiently access the data. So the system has all banks with universal validity range and its own machinery for synchronisation based on run number.
Masks will be stored in 2 types of bank: DAMN and DARN.