HP Color LaserJet 5500 Technical Reference Manual page 65

Each environment is explained in more detail below:
Factory Default Environment — This environment
consists of a group of feature settings that are
permanently stored in the printer. The printer uses these
settings when it is powered on for the first time after
leaving the factory, and after the INITIALIZE command
is received.
User Default Environment — This environment
contains the values that are set using the DEFAULT
command or the control panel keys. These values are
stored in non-volatile RAM (in those printers containing
NVRAM). Following any PJL reset condition, these
values are placed into the PJL Current Environment. If
the printer has a control panel, the User Default values
are displayed on the control panel under the appropriate
menu.
PJL Current Environment — This environment
contains the current PJL feature settings. Current
settings are based on the User Default values and any
settings modified using the SET command. These values
default to the User Default values when a PJL reset
condition occurs.
Modified Print Environment — This environment is
active as soon as a printer language is entered. At that
time, the PJL Current Environment values are loaded
into the Modified Print Environment and act as a base
set of features. Printer language commands then are
used to modify feature settings to the desired state. The
PJL Current Environment settings are loaded into the
Modified Print Environment whenever a personality is
activated or a reset is received, including any printer
language reset or PJL reset condition.
Figure 6-1 illustrates how the environments interact, and
how they affect the modified print environment.
Environment Commands 6-3