HP Color LaserJet 5500 Technical Reference Manual page 246

PJL Job Security
A-34 Feature Support
There are two differences between backward-compatibility
mode and normal operating mode. In
backward-compatibility mode, when a PCL printer
language reset (<ESC>E) is executed, instead of causing
the PJL Current Environment variables to be loaded into
the Modified Print Environment, the User Default
Environment settings (control panel values) are loaded.
This is the same way the LaserJet III printer works.
Note
Because HP LaserJet 4L and 5L printers do not support job
boundaries (JOB/EOJ), they always load the PJL Current
Environment variables into the Modified Print
Environment after receiving an <ESC>E reset.
Also, when a backward-compatible job ends with a partial
page (one not terminated with a form feed or PCL printer
language reset) and the job times out, the job does not
immediately end, printing the partial page. Instead, the
printer waits to see if the next job sent consists of more
PCL data (from the same I/O port), which it then appends
to the partial page already in the printer. (This works the
same way as the HP LaserJet III printer, which does not
have a job timeout.) If PJL data is received instead, the
partial page is printed before the new PJL job is executed.
Printers that support PJL job security:
HP LaserJet 4/4M Plus, 4V, 4MV, 4Si, 4SiMx, 4000 series,
5, 5M, 5Si, 5SiMx, 5Si Mopier, (5P, 5MP, 6P, 6MP: pass-
word only)
The printers listed above provide two PJL security features:
password protection and control panel lockout. HP LaserJet
4V/4MV and 5Si/5SiMx printers also provide disk lock
protection. As discussed in Chapter 5, the DEFAULT
command can be used to set a PJL password. Once the
password is set, all succeeding jobs must issue the
correct password in order to enable the DEFAULT and