Passenger’s personal information like name, age, gender, etc. is saved in the database against this reference number. It includes columns to store the booking status and current status of the ticket. As we know every train has a limited number of seats, sometime one may not get a confirmed reserved ticket. Booking status of such waitlist (W/L) ticket changes when there is any availability of reserved seats due to cancellation. This new current reservation status is generally known as PNR status.