TA90 Cartridge Tape Drives

[angel at BRL.MIL]

We have a VAX 6320 with TA90 cartridge tape drives (a.k.a. IBM 3480).
Is there a command to do a software unload of the cartridge from the
unit?  There is a stacker on the tape drive which holds up to 7-8 
cartridges - the ability to do an automatic unload of the tape from 
software would be of enourmous benefit (such as a "hands-off" backup 
by the operators).    The documentation included with the device does
describe VMS commands for doing a software unload of the tape (Grrrrr.....)
I have not found any comparable command in the Ultrix 3.1 documentation set.

Any help would be appreciated.