HP Color LaserJet 5500 Technical Reference Manual page 106

Comments:
The SET command enables you to specify either general
variables which are used by all personalities, or printer
language-specific variables. Printer language-specific
variables must be specified using the LPARM : personality
option. Features that are not printer language-specific
cannot be specified with the LPARM option.
All port-specific variables must be set using the IPARM :
port option. Variables that are not port-specific cannot be
set using the IPARM : port option.
Values modified with the SET command do not affect the User
Default Environment values. Feature settings changed with
the SET command are valid until the next PJL reset condition.
A separate SET command must be sent for each
environment variable you specify. The command may be
used to set any environment variable except CPLOCK,
DISKLOCK, PASSWORD, and the read-only variables. See
the "Environment Variables" section of this chapter for a
discussion of each environment variable.
Note
If the SET command is used in a job, use the RESET
command after the job to reset features to the User Default
(control panel) values. See the following example for a
demonstration of how to use the RESET command to "clean
up" after using SET.
6-44 Environment Commands