Some of the Datacom system databases are opened in MUF, for example:
DB00903I - OPENED, BASE - 1006DB00903I - OPENED, BASE - 1007DB00903I - OPENED, BASE - 2009
but a query on MUF_OPEN_BASES Dynamic System Table doesn't return any row for these ones
Datacom/DB
Datacom/AD
The MUF_OPEN_BASES table shows jobs that have an open User Requirements Table (URT). User programs accessing tables must have those tables open to access.
Datacom System databases are special. Some do have URT's and those will be reported. Some do not.