to use ISAM to use a KSDS instead. The RRDS organization was designed to replace BDAM, the Basic Direct Access Method. In some cases, BDAM data sets contained embedded pointers which prevented them from being moved. However, most BDAM data sets did not and the incentive to move from BDAM to VSAM RRDS was much less compelling than that to move from ISAM to VSAM KSDS. Linear data sets were added later, followed by VSAM RLS and then Transactional VSAM. See also Job Control Language (JCL) IBM mainframe utility programs ISAM Geneva ERS Record Management Services, a similar system developed by Digital Equipment Corporation Notes References VSAM Demystified DFSMStvs Overview and Planning Guide IBM mainframe operating systems IBM file systems Computer file formats