Apple LaserWriter 12/640 PS - Manual (Page 199)

Letterhead paper and three-hole punched paper
Insert letterhead paper into the paper cassette face down, with the top of the
letterhead at the front of the tray (the handle end).
Note: If you want to print on both sides of the letterhead paper, place the
letterhead paper face up in the paper cassette, with the top of the page closest
to the handle.
Insert three-hole punched paper into the paper cassette so the holes are
toward the left side of the cassette.
Using the multipurpose tray
The multipurpose tray can hold up to 80 sheets of various sizes, as well as
envelopes, transparencies, and sheets of labels. The exact number of sheets
the multipurpose tray can hold depends on the weight of the paper. You can
use the multipurpose tray in several ways:
m automatic printing
m manual feed printing
m envelope printing
m postcard printing
m transparency and label printing
Note: You cannot duplex print when the paper source is the multipurpose tray.
Adjust the length and width guides
to fit the size paper you’re using. Align letterhead and three-hole
punched paper as shown.
199 Loading Paper