For nonspecific mount requests, where a specific scratch pool is required, DFSMSrmm updates the message text with the pool details. If you use the EDG_EXIT100 installation exit to select a specific pool, DFSMSrmm updates the message text and checks the cartridge loader status. If you requested the loader be disabled for a specific pool, DFSMSrmm sets bit 7 of the format control byte to zero.

For specific mount requests, DFSMSrmm checks the volume and uses the volume serial number to determine the rack number and updates the message text with the rack number. If you use the EDG_EXIT100 installation exit to specify a rack number or an external volume serial number for a volume that DFSMSrmm should ignore, DFSMSrmm uses the value you specify to update the message with the rack number.