HP Color LaserJet 5500 Technical Reference Manual page 59

To write to volume 0 of the file system, you would send a job
like the following. This job specifies the correct password
with the JOB command, and then uses the DEFAULT
command to unlock, and then later to lock the disk.
<ESC>%-12345X@PJL <CR><LF>
@PJL COMMENT **Unlock Volume 0** <CR><LF>
@PJL JOB PASSWORD = 1776 <CR><LF>
@PJL DEFAULT DISKLOCK = OFF <CR><LF>
@PJL DINQUIRE DISKLOCK <CR><LF>
@PJL ENTER LANGUAGE = POSTSCRIPT <CR><LF>
%!PS-ADOBE . . . PostScript print job . . . ^D
~<ESC>%-12345X@PJL <CR><LF>
@PJL COMMENT **Lock Volume 0** <CR><LF>
@PJL DEFAULT DISKLOCK = ON <CR><LF>
@PJL DINQUIRE DISKLOCK <CR><LF>
@PJL EOJ <CR><LF>
<ESC>%-12345X
Job Separation Commands 5-13