[css3-values] <positive-integer>

On multiple occasions, I've run into spec concerns related to not indicating directly in the grammar that negative values are not allowed.

Shouldn't there be tokens such as <positive-integer> that can be used directly rather than using <integer> and then relying on prose to say zero and negative are invalid?


Something like ...

<positive-integer> = [0-9]+
<negative-integer> = -[0-9]+
<non-negative-integer> = <positive-integer> | 0
<integer> = <non-negative-integer> | <negative-integer>


Similarly for <number>.