For nonspecific volume requests, the media type assigned to the cartridge loader is preferred if data class is not specified through the data class JCL parameter or through the ACS filter routines. If that scratch category is empty, an appropriate alternate media type is selected. However, if the category assigned to the cartridge loader is NONE, then MEDIA2 is preferred for a 3490E, and MEDIA4 is preferred for a 3590. MEDIA5 is preferred for a 3592 Model J, with MEDIA7 as the alternate media type. MEDIA5 is preferred, with MEDIA7 as the alternate media type when EFMT1 recording format is requested on a 3592 Model J or 3592 Model E05 drive. MEDIA9 is preferred, with MEDIA5 and MEDIA7 as the alternate media types, using the EEFMT2, EFMT3, or EEFMT3 format, or when no recording technology has been specified and a 3592 Model E05 or 3592 Model E06 is allocated. MEDIA11 is preferred, with MEDIA9 and MEDIA13 as the alternate media types using the EFMT4 or EEFMT4 format, or when no recording format has been specified and a 3592 Model E07 is allocated. MEDIA9 is the only applicable media type when using the EFMT3 or EEFMT3 format and a 3592 Model E07 is allocated. 3592 WORM media (MEDIA6, MEDIA8, MEDIA10, and MEDIA12) can be used for a nonspecific volume request only when explicitly requested through data class. If a specific media type is selected using data class, only that media type is used.

If a data set spans multiple volumes, the subsequent volumes are written using the media type of the last volume written. If the scratch category for the media type is empty, rather than fail the job, an appropriate alternate media type is selected.