Apple LaserWriter 12/640 PS - Manual (Page 210)

3 Choose an option.
4 When the selection is as you want, choose another setting from the Settings pop-up
menu, or click Print.
Reporting errors
You can specify what happens when a PostScript error occurs or when the
paper cassette runs out of paper. For PostScript errors, you can have the
printer provide no reporting, provide a summary of the print error on your
computer screen (when using foreground printing), or print a page reporting
the error. When the printer is out of paper, you can have the printer use
another cassette with the same paper size or display an alert message.
If you select “Switch to another cassette with same paper size,” the printer
will get paper from its input trays in the following order: standard cassette,
multipurpose tray, optional 500-cassette, optional envelope cassette.
IMPORTANT If you have the same size paper in your paper cassettes and
multipurpose tray and have tray switching turned on, the printer may draw
paper from any paper source that has the correct size paper (even if you
select a specific paper source from the Print dialog box). If you want to print
from a specific paper source only, do not select “Switch to another cassette
with same paper size.”
185 Mac OS Users