Hello! Quick question about the reference numbers with the operator (?) BREIHGO_CAR. Are there really 4 different operators that differ in name by a two-digit number? Or are these just an (internal) zone ID of an operator to define areas of use? This refers to the keys
gtfs:BREIHGO_CAR_22:stop_id
gtfs:BREIHGO_CAR_29:stop_id
gtfs:BREIHGO_CAR_35:stop_id
gtfs:BREIHGO_CAR_56:stop_id

In the latter case, I would recommend transferring this to an extra key.
gtfs:BREIHGO_CAR_22:stop_id=x would become 
gtfs:BREIHGO_CAR:stop_id=x and 
gtfs:BREIHGO_CAR:zone=22