HP PCL/PJL reference - Printer Job Language Technical Reference Manual

EN Programming Tips for Using PJL 11-3
Print Data Generators
Print Data Generators are applications used to create and print
information. Examples include WordPerfect, Harvard Graphics, and
Lotus 1-2-3.
Software applications of this type should work properly when the
printer is under the direct control of the application, and also when
there is a spooler between the application and the printer. This is
accomplished by using the ENTER command to select the proper
printer language before sending print data to the spooler or printer.
The UEL command should precede and follow the print job.
Print Data Generators should only use PJL commands when a
corresponding command does not exist in the printer language. This
is recommended so that the application does not override feature
settings and adversely affect future jobs. To change feature settings
for the duration of the job, or until the next PJL reset condition, use
the SET command. Do not use the PJL INITIALIZE command for
Print Data Generators.
Commands Used by Print Data Generators
UEL Use before and after every PJL job.
COMMENT Use to add explanations within PJL code.
ENTER To select the correct printer language for the print
job.
SET To select a desired feature when it is not possible
using the desired printer language (such as PCL
or PostScript).
RESET Use at the end of the job if the SET command is
used in the job.