Originally Posted by
Dave Noble
The airline has cancelled a sector and a rerouted journey has been offered
An actually cancellation of the ticket would have to be initiated by the passenger and , depending on how much of journey has been undertaken already , once a fare for the actual journey undertaken is calculated could find that there is not much of a refund due
That's a roundabout way of saying that like me you have no answer to the specific question the OP has asked ie how that calculation is made and where he can find the rules for that calculation