[css3-mediaqueries] Is (width) ever false?

http://dev.w3.org/csswg/css3-mediaqueries/#media1 says:
  # For a media feature feature, (feature) will evaluate to true if
  # (feature:x) will evaluate to true for a value x other than zero.

Does this mean:

  (a) (width) is always true, even if the viewport width is zero,
  because "0px" is a value other than zero, or:

  (b) (width) is false when the viewport width is zero because "0px"
  and "0" are both not "other than zero"?

I'd also note that because specified widths cannot be negative,
(max-width) currently behaves the same as (width), whereas
(min-width) is always true.  Is that really intended?

-David

-- 
L. David Baron                                 http://dbaron.org/
Mozilla Corporation                       http://www.mozilla.com/