Multiple file format requires a unique standard-label data set for each user data set. Each tape data set has a file sequence number associated with it that can have a value from 1 to 9999. After DFSMShsm writes a user data set to tape, it checks the file sequence number of the file just written. If the sequence number is 9999, the currently mounted tape is marked full and is deallocated. DFSMShsm selects another tape and writes the next user data set with a file sequence number that is one greater than the last file on the newly mounted tape. Empty tapes start with a file sequence number of one.