An object that with-print-job uses when a pane is not supplied.
printer-port is the class of the object that with-print-job binds its
argument to when it is not given a pane.
The phrase "printer port" refers to either to an instance of
printer-port or an instance of output-pane when it is used as the pane argument to with-printer-job.
CAPI User Guide and Reference Manual (Macintosh version) - 25 Feb 2015