CSS2.1: computed value of z-index

http://www.w3.org/TR/CSS21/visuren.html#z-index

z-index only applies to positioned elements, however, its computed  
value is "as specified". Since the computed value can be exposed to  
script via getComputedStyle(), I suggest that it would be more useful  
if the computed value is "as specified for positioned elements,  
otherwise auto" so that scripts get the value actually used.

[Side note: the spec also says "In future levels of CSS, other  
properties may introduce stacking contexts, for example 'opacity'."  
Does that mean z-index should apply to non-positioned elements  
affected by such properties? Hyatt tells me this is already an open  
question for CSS3.]

Regards,
Maciej