[css3-transforms] UA supporting only 2D transforms

Hi,

It’s been discussed on this list a few times here but I don’t remember 
if there was a conclusion. More importantly, I can’t find a definitive 
answer in the ED.

What should an UA do if it only wants to support or can only support 2D 
transforms?

The "Partial implementations" section seems to indicate that any 
'transform' property declaration or attribute value should be considered 
invalid if it contains a 3D functions. (2D and 3D functions already are 
in different spec section, so that’s good.)

Similarly, I suppose that the 'transform-style', 'perspective', 
'perspective-origin' and 'backface-visibility' are ignored. Or should 
the values that establish a stacking context still do that?

The more tricky part is transform-origin with three values. Should a 
3-value declaration be invalid? Or should the third just be ignored?

-- 
Simon Sapin