The system only keeps the number of generation data sets that the user specifies. If for example a limit of 4 was specified, when the 5th generation data set was created the system would uncatalog the 1st. Each subsequent new generation would cause the system to uncatalog the oldest generation retaining only 4 in the OS catalogue. For these tapes processing is virtually unchanged. This tells TMS to treat this tape as a private or foreign tape and not to perform all of it's security checking.
All private tapes require the use of the volup procedure.
More than one data set may be stored on a single tape. Multiple data sets may be written out to tape when it is originally created. The user may also add additional data sets to the end of the tape later, but TMS will issue a warning message if all data sets contained on the tape do not have the same expiration date. The tape will not be expired by TMS until all data sets on it have expired. TMS also protects the data sets stored on a tape by not allowing the user to recreate or mod to a data set that is not the last one on the tape.