Name of print job files printer on shared printer

Hello,

Can somebody explain the rules Windows XP uses to give
names for the spool files of shared printers in
\Windows\System32\Spool\Printers directory .
I know how Win NT and 2K make this.
(Example) job ID 36 spool file is named '00036.spl'
But in the XP, print job files spooled after network
printing (from other PC) are named for example
FP00000.spl, or some else..
In other word I'm looking for the relation between
job's ID# and it's spool file name..

Thanks,
Zdravko