what does the last sequence of characters in the following PIDs signify?

    PID: ALLFIX+ 6.00.18 EFF59863
    PID: ALLFIX/2+ 6.00.18 A397509A

is it supposed to be a MSGID serial number or is it some kind of registration
number?

the reason i ask is because i'm seeing some allfix v6.0 announcements in my
dupes area... none of them have MSGIDs... however, my allfix 5.13 does
generate proper MSGIDs and it also has similar numbers to the above on the PID
line...

thanks for any help with this!

)\/(ark

 * Origin:  (1:3634/12)