Flying SIN to YVR to YUL on AC.

SIN to YVR is ineligible for OSS. I have to walk a very long way to a passport control followed by a security check.

It appears the security check is the priority security checkpoint 3 I used to use a lot (the one behind the priority checkin counter for AC domestic.

I do not know how the airport is configured but it does not seem during my walk there is any confusion for me to go to the usual ITD passport control which does not require another security. In a few week I will fly SYD to YVR so I can observe the difference.