To request that no automatic cartridge loading be performed, use the IGXMSGEX routine to set bit 7 in the format control byte to zero. To request automatic cartridge loading, set bit 7 to one.

When IGX00030 receives control back from IGXMSGEX, it processes according to the fields that IGXMSGEX might have modified in the two display data fields and in bit 7 in the format control byte when it issues the LOAD DISPLAY channel command. IGX00030 also checks to see if the device in the UCB in the parameter list supports automatic cartridge loading if it is active. If the device does not support automatic cartridge loading and IGXMSGEX set bit 7 to one, IGX00030 resets the bit to zero before issuing the LOAD DISPLAY channel command.

If IGXMSGEX is not link-edited with IGX00030, MSGDISP allows automatic cartridge loading only if the device supports automatic cartridge load, and if the volume serial number is either SCRTCH or PRIVAT.