Syntax:
default jukebox_spec location [ location] [ location]
The default command, a.k.a the set command sets the default port, drive, or slot location for other commands. If the location specified is a drive location it sets the default drive, if the location specified is a port location it sets the default port, and if it is a slot location it sets the default slot.
Note that this means default mytape sets a different default depending on whether the tape is in a slot or drive...