QMS 2425 Reference page 149

If you are printing via the serial and parallel protocols, and one of the
following conditions exists, you may need to set the end job mode:
Multiple print jobs with little or no time delay and with no EOD
commands have been sent to the printer and the message win-
dow displays only one active job.
Multiple print jobs of the same printer language have been sent to
the printer and they print on the same page. (For example, you
send the AUTOEXEC.BAT file with no EOD command followed
with little or no time delay by the CONFIG.SYS file, and they both
print on the same page.)
Multiple print jobs of different printer languages "run" together as
if they are a single print job. (For example, you send a PCL print
job followed by a PostScript print job, and the PCL job prints and
is followed by what appears to be program code instead of your
PostScript print job.)
You want to print multiple jobs with header pages.
You want to print multiple jobs where job separation is important.
When your printer is in ESP mode, printing multiple jobs through the
serial and parallel protocols and end job mode is not set, ESP tech-
nology interprets the emulation for only the first job. The print jobs that
follow are interpreted as being the same emulation as the first job. For
example, if there are two print jobs, the first a PCL file with no EOD
command, and the second a PostScript file with a Ctrl-D (a PostScript
end-of-file character)—ESP technology interprets the emulation of
the first job correctly. But since the first print job has no EOD com-
mand, it "runs" into the second job, and even though the second job is
PostScript, it prints in PCL.