Legal values are (from IATA resolution 792):
'0': Ticket issuance/passenger not checked in
'1': Ticket issuance/passenger checked in
'2': Baggage checked - passenger not checked in
'3': Baggage checked - passenger checked in
'4': Passenger passed security check
'5': Passenger passed gate exit (coupon used)
'6': Transit
'7': Standby. ...
'8': Boarding data revalidation done. ...
'9': Original boarding line used at time of ticket issuance
'A': Up- or down-grading required. ...
'B' - 'Z': Reserved for future industry use
NB! All other values than '0' indicates that the passenger is checked in. | 