I noticed that my electronic boarding pass for my flight from Montreal to Charlottetown this afternoon had ITD OSS above the QR code, which I’d never seen before.
Some poking around revealed this this is an indicator for International To Domestic One Stop Security, and is the new system at Trudeau Airport that allowed me not have to exit customs, go back groundside, and go back through security again to continue my journey when connecting from the Boston to Montreal flight.
This is the first time I’ve benefited from this: upon arrival in Montreal, I was directed to a special customs area for connecting passengers. I went through the normal customs procedures, and then exited directly into the airside departures area.
This was a huge time and anxiety saver: at busy times in Montreal, having to exit and re-clear security could add 45 minutes to a connection.