Mr. Harmless, that's what I thought. However the Canadian AIP , quote above, does not go into that detail. See my post 1 for the full quote. Specifically it says
"an aircraft that is flown on a straight-in approach at 135 KIAS is to use the Category C". Now, at max landing weight that might be 141 kts, which would be a cat D aircraft under US and ICAO rules, and perhaps higher minimums for Cat D versus Cat C.
"Flown" is the word in the AIP, I take that to be (normally) VRef. No mention of Max landing weight, no mention of not changing categories to a lower one, no mention of being in one category only unless faster, no mention of being certified to one category only (Canadians, that is, the US and ICAO do say differently). Only that the category is determined based on speed "flown".
As I said, the US and ICAO are quite specific about the one category only.
Do you have additional information on this for flights in Canada?