For nonspecific volume requests, the cartridge loader media type assignment through the LIBRARY SETCL command plays an important role. It lets the system know the intended use of the cartridge loader and whether indexing is to occur on this system. If indexing is to occur, it indicates what media type should be loaded in the cartridge loader. If a media type is then preferenced through DATACLASS, an attempt to index the cartridge loader is made only if the media type that is assigned to the device matches the DATACLASS specification. If DATACLASS does not specify a media type, indexing occurs on those systems where the cartridge loader is not set to NONE. If there is no intention to preference a specific media type, all of the cartridge loaders could be set to ANY. This then enables you to load any appropriate media type for the device. After an IPL, the cartridge loaders, by default, are set to NONE.