HP Color LaserJet 5500 Technical Reference Manual page 69

Factory Stored permanently in printer memory—settings cannot be modified.
Default
Factory default settings cannot be read programmatically, but they are
Environment
listed in the PCL 5 Comparison Guide.
User Default The User Default Environment is set to the factory default values when
Environment the printer initially is powered on—before printer commands are sent
from an application or any control panel settings are changed.
Stored in non-volatile RAM in printers that have it—can be changed
using the DEFAULT command or control panel keys.
The INITIALIZE command loads the Factory Default settings into the
User Default Environment.
User default settings can be read using the DINQUIRE command.
PJL Current Any PJL reset condition loads the User Default Environment feature
Environment settings into the PJL Current Environment.
Always reflects the PJL-level settings currently in use.
Stored in RAM—can be changed using SET command. These values
override feature settings until the next PJL reset condition.
The INITIALIZE command loads the Factory Default settings into the
PJL Current Environment.
PJL Current Environment settings can be read using the INQUIRE
command.
Modified Print Active as soon as printer receives any printer language commands
Environment (such as PCL or PostScript commands). This environment contains all
(Printer- of the feature settings currently in effect at any point after a printer
Language language is entered.
Specific)
Printer language resets (such as the <ESC>E command in PCL), any
printer language switch, or the ENTER command load the PJL
Current Environment into the Modified Print Environment.
Stored in RAM—can be changed using printer language commands
(PCL, PostScript, and others). The printer language values override
any PJL Current Environment feature for the duration of the printer
language job (until the printer language is changed or a printer
language-specific reset is executed).
The Modified Print Environment settings can be read if the active
printer language supports this capability.
Environment Commands 6-7