[css3-background] border-image dependancies on border-style and border-width

I was noticing on caniuse.com[1] that they have this note about border-image:

Note that both the border-style and border-width must be specified for border-images to work according to spec

But that shouldn't be true unless you are setting border-image-width to a number instead of a length or percentage. Am I missing something, or is caniuse.com wrong?

P.S. I think it is kind of unfortunate that having 'border-style:none' changes the computed value of border-width to 0, regardless of what the author sets, since I think that is why border-style has to be explicitly set in order for 'border-image-width:[number]' to work. But I imagine it is way too late to change that. But could we have border-image-width use the cascaded value of border-width instead of the computed value?

1) http://caniuse.com/#feat=border-image