The PNR Numbers' starting digit does not depends upon the PRS from which it has been booked.
It actually depends upon:
* "Zone of the Train, wrt Starting station of the train" ,irrespective of zone of any intermediate journey starting stn."
For eg: If a ticket is booked in Karnataka Exp, from New Delhi to Manmad it will Start from 2, as trains starting...
more... station Ndls is in NR while if its from Manmad to Ndls it will start from 4, as trains' starting stn is SBC in SWR even if both tickets r booked at Howrah stn.
The number as per PRS of zone of stations' is:
¤ 2,3: NR, NCR, NWR, NER
¤ 4,5: SR, SWR, SCR
¤ 6,7: NFR, ECR, ER, ECoR, SER, SECR
¤ 8,9: CR, WCR, WR