QMS 2060 Reference page 143

When sending print jobs through the serial and parallel protocols,
some applications and their printer drivers append an end-of-docu-
ment command (EOD) to each print job to ensure that each file prints
correctly. The reason for this is that some protocols and print queuing
systems send print jobs to the printer as one continuous data stream
(one print job immediately following another).
But the problem with this system is that some applications are limited
by the printer language and are unable to produce an EOD com-
mand. This becomes even more problematic when you're printing to a
QMS 2060 Print System, where print jobs of all supported emulations
can be received simultaneously. ESP technology examines the first
part of each print job to determine its emulation. Once the emulation
is identified, the print job processes without further checking. This
minimizes any slowdown resulting from the sensing process. To help
ESP technology determine the proper emulation of successive print
jobs, the printer must be able to identify the end of job for each job.
Therefore, unless a wait timeout (the amount of time the printer is
waiting on data from the host) occurs and ends each print job, or
unless you add an EOD command between each file being printed
through these protocols, some print jobs may be interpreted by the
printer as one job and may "run" together. See chapter 4, "Printer
Configuration," for more information on emulation timeout.
When printing multiple jobs with little or no time delay and with no
EOD command between each job, the serial and parallel protocols
may be unable to detect an end of job automatically. So the End Job
Mode feature on QMS Crown printers was designed to allow you to
set the end of document for print jobs being sent through these proto-
cols.