This figure illustrates how you can set locks to cover data files as determined by your settings for the GC_FILES_TO_LOCKS parameter.
There are two disks, each disk containing data files. In disk one, datafiles one, two, and three have 120, 60, and 100 data blocks respecitvely. Datafile one has 60 locks assigned to it, and two of the 120 blocks are marked as covered by one of these 60 locks. Datafiles two and three are also on this disk, and these datafiles share 40 locks. Datafiles two and three can have either 3, 4, or 5 blocks covered by one lock at any time. Datafile two appears with 2 blocks covered by one lock while datafile three shows 3 blocks covered by one lock.
The second disk has two datafiles, datafiles four and five. Datafile four has 140 data blocks covered by 1 lock (this is probably a read-only table), and datafile five has 5 or 6 data blocks covered by a lock.