Yes, I would say that having clear definitions is helpful in terms of making sure that globally we're addressing this issue in the same way. I do take the point that sometimes we get so lost in these definitions that we miss the forest for the trees, and that can be very dangerous.
I think a simple definition is that any type of public support—public funding—that goes to the sector is a subsidy and has to be eliminated.
My worry with “inefficient” is that because there is no agreed-upon definition for “inefficient”, governments like Canada's can use that as a loophole to continue subsidizing the fossil fuel sector. Countries like Italy, as you heard the other day, have just said that all subsidies are inefficient, so that's one way to approach it.
I think there's a balance between making sure that we have agreed-upon language that doesn't let governments use weasel words to get out of real action but that also lets us have comparable targets with our peers.