Yes, I'd like to come in on this, if I could, Madame.
First of all, I think we should note that how a convention solidifies into constitutional law is one of the great mysteries of constitutional law. I think there are different ways in which that can come about.
The most obvious way, as has been mentioned already, is through history and precedent, that this is the way it's been done, and been done over again, which then takes on a certain legitimacy and expectation on the part of all political actors. That's what the Supreme Court relied on in the patriation reference, saying that under black-letter law, yes, Ottawa, you can do it, but under convention, no, because you must have substantial provincial consent.
But the Supreme Court, in the Quebec secession reference, also displayed a second basis for developing a convention. That was not based on history and precedent but on what the Supreme Court said were the fundamental values underpinning Canadian federalism. That's what made it a constitutional convention that Ottawa would have to negotiate with Quebec.
Thirdly, there can be a catalytic event, which I think can establish a convention very quickly. Arguably, the Charlottetown reference is such an example. Some people—and I think I would be one of them—would argue that even though we've only done that once, we will never again make a substantial constitutional change without popular consent.
So there are many ways to skin the conventional cat.