Oki C5400 Reference page 71

From the various options presented, make your desired
4.
selection.
Auto Select
If you have identical paper stock loaded in the Multi-Purpose Tray or
the optional Second Paper Tray, you can have the printer
automatically switch to the other tray when the current tray runs out
of paper.
Paper Options (Plain Paper, Letterhead, etc.)
When you select a paper-type option, the printer automatically
accesses the proper tray. For example, when Labels is selected, the
printer will pull from the Multipurpose tray where the labels should be
inserted.
Tray Options (Tray 1, etc.)
Select the paper source desired for the current print job.
Macintosh OS X: Operation • 71