One additional point in this very useful thread.
I flew AMS-CAN-AKL, entering China on TWOV. Checking in with KL in AMS they issued one single boarding pass covering both flights. This caused some confusion on departure from CAN going through the various security checks, they had to go off and ask a supervisor. I would recommend anyone in possession of one of these boarding passes to insist that the transfer desk issues a new CZ boarding pass for the onward flight.