Just a side note, but I think Montreal is the only city in Canada that uses this terminology. Definitely the 1/2 refers to a bathroom.
3 1/2 = kitchen, living room, bedroom, bathroom
4 1/2 = kitchen, living room, 2 bedrooms, bathroom
and so on.
I have no idea if it's standardized. What happens if there are two bathrooms, for example?
Do they differentiate between bathrooms with just a toilet and sink, or bathrooms with the whole jacuzzi tub and shower? Hehe...
Elsewhere in Canada, you'd just see "one bedroom apartment" or "two bedroom apartment" or "two bedroom apartment with den", etc.