I think I posted something about this a little while ago. Change fee for HKG is $50 whereas for Europe in can be 2 or $300. And these are W/S fares:

From the fare rules

Changes:

* Prior to day of departure - Change fee per direction, per passenger, is $50 CAD plus applicable taxes and any additional fare difference.
* Day of departure, at the airport - $100 CAD, per passenger, plus applicable taxes (no charge for fare difference) for same-day flights only.
* Flights can only be used in sequence from the place of departure specified on the itinerary.

# Cancellations:

* Tickets are refundable (a $200 CAD fee applies per person) and non-transferable.
Partially used tickets may be submitted for a refund assessment. The refund will be calculated as follows: actual fare paid minus the value of the portion of the journey that has been flown, and minus the applicable fee.
* Cancellations can be made up to 45 minutes prior to departure.

These are quite flexible fares