Originally Posted by
LHR/MEL/Europe FF
We don't know if they will look at it as being less than 24 hours, therefore you're only eligible for 24 hours (and hence can no longer get it or leave the airport). Chinese immigration is usually pretty practical, so I'm guessing they'll let you in on the 72 hour version.
I'm guessing the opposite, that the deciding factor will be the less-than-24 hours layover, and that the poster will be granted TWOV but not permitted to leave the airport. With 17 hours to kill at CAN, that would be a bummer.