If file generations are stored on tapes, the user must remember that the group entry exists only in the file catalog of the pubset on which the FGG and its generations were cataloged. It is not transferred to tape. The file generations are identified as such in the HDR1 label of the tape by the fact that they have generation numbers.
Just like other tape files, file generations may also extend over several tapes, or there may be several generations on a single tape. Volumes which become free can, however, be reused (DISP=REUSE or OVERFLOW-OPTION=REUSE-VOLUME) only if the file generations are not stored as file sets. Instead, each must be stored as a single file on a tape or in a volume set.
Just like FGGs and generations on private disks, file generations on tape can be exported and imported again at any time.