That’s how it works in T1 as well. At T1, when the proceeding letter is ‘D’ it’s for domestic, when it’s F it’s for transborder and E is for international. There are some gates that can be used for either domestic or US departures, so those gates (mostly or maybe all in the low-mid 50s, I think?) start with D or E depending on the flight. There are also some E gates that can be used for transborder departures and so are E/F gates - they are in the 70s - though I’m not still if they use them for both anymore - they were typically used for US departures in the peak morning bank, and than international all other times. However, not sure if they ever use them for transborder since they opened the other side of ‘the barn’ - those gates in the 90s that United typically uses, AC too.

and if Canadian airport history ever becomes a Jeopardy category, might be good to know some history - when the ‘new’ T1 opened, the gates were all 3 digit numbers and didn’t use the letter designations ahead of the two-digit numbers until later (T3 might have been the same way, I’m not sure). These numbers indeed are still referenced - for example, if you look at flight status on United’s website for any inbound flight to YYZ, they show those old 3 digit numbers as their arrival gate - the departures show the ‘official’ ‘F’ numbers. For example, today, UA 5450 from ORD shows the arrival gate as ‘162’ - that aircraft turned as UA 5578 back to ORD, leaving from gate ‘F62’.