Eamonn O Brien
Oh I know that man, I'm just gettin' into the Admiralty side of things now... Wrapping my head around it will hopefully make everything else more understandable...
I'd imagine a PPS/SIN could be referred to as a stock code... Once you use it it relates back to the Government's "cargo" on the "vessel"...
"Oh you're wanting to bring our cargo inland I see... We'll have to issue a license for that Captain"... etc... :p