HP Color LaserJet 5500 Technical Reference Manual page 17

and possibly followed by more PJL commands. The PCL job
should print as it would without any PJL commands, as
long as the PCL portion of the job begins and ends with a
PCL printer reset command. However, a page of PJL
commands printed before and probably after the PCL job
can be expected.
For those PCL applications that do not begin with a PCL
printer reset command (or another PCL command that
forces a page eject when preceded by printable data), the
PJL commands are printed as ASCII text on the same page
as the PCL job. A good portion of the job may be unusable
due to unpredictable page breaks and overprinted text on
the first page.
PostScript Jobs
When non-PJL printers are running in PostScript mode,
PJL commands cause a PostScript error and prevent the job
from printing. Pressing the printer's Continue key removes
the error message, but the error causes the printer to
discard the PostScript job.
Other Printer
PJL code is interpreted differently when running different
printer languages on non-PJL printers. To avoid printing
Languages
problems, do not use PJL commands when printing to any
non-PJL printer, regardless of which printer language is
used.
Introduction to PJL 1-5