If you do not specify an accessibility code on a DD statement that defines an ISO/ANSI/FIPS Version 3 or ISO/ANSI Version 4 tape data set, the system writes an ASCII blank character (X'20') in the tape label. A blank authorizes unlimited access to the tape's data sets unless access is limited by RACF® data set protection.

If the installation does not supply a file-access exit routine, the system prevents access to any ISO/ANSI/FIPS Version 3 or ISO/ANSI Version 4 tape volume.