The curves represent values versus time (eg x vs. t, y vs. t, z vs. t, angle vs. t). Blender indeed ensures the the Bezier curves are a proper functions.
As I said in my second post, I am of course aware that there are some 2-D Bezier curves which would not make sense in this context. However, I still see absolutely nothing wrong with it. Artists should have the power to define nice curves and it is up to the programmer to worry about the math.Originally Posted by sthomas
Anyway, it is not up to us to decide. I downloaded free version of Maya and it seems to handle animations the same way as Blender. I do not have Max, but I guess it will do it the same way as well.
EDIT: Note that strictly speaking there is nothing wrong with the Collada specification itself - it mentions the in-tangents and out-tangents, but it does not define their format (as far as I know).