Apple ColorLaserWriter 12/600PS - Manual (Page 237)

4 Insert your paper within the guides.
5 Set the size guide on the front to match your paper’s size.
Setting this guide indicates to the printer the size of the paper in the cassette.
6 Insert the paper cassette into the printer (or into the 250-sheet feeder).
LGL
A4
LTR
B5
Size guide
Load three-hole punched
paper with the holes toward
the back of the cassette.
Load letterhead
paper face up.
Make sure paper fits under
these corner brackets. ABC
Do not stack paper
higher than this point.
213 Loading Paper