[css-values-4] Second try at abs(); I have to refer to the numeric value, not just the calculation itself.

Author: tabatkins

css-values-4/Overview.bs

@@ -3286,16 +3286,15 @@ Sign-Related Functions: ''abs()'', ''sign()''</h3>
 	contains one [=calculation=] A,
 	and returns the absolute value of A,
 	as the same [=CSSNumericValue/type=] as the input:
-	if A is positive, just A again;
-	if A is zero, 0⁺;
-	if A is negative, ''-1 * A''.
+	if A's numeric value is positive or 0⁺, just A again;
+	otherwise ''-1 * A''.
 
 	The <dfn lt="sign()">sign(A)</dfn> function
 	contains one [=calculation=] A,
-	and returns -1 if A is negative,
-	+1 if A is positive,
-	0⁺ if A is 0⁺,
-	and 0⁻ if A is 0⁻.
+	and returns -1 if A's numeric value is negative,
+	+1 if A's numeric value is positive,
+	0⁺ if A's numeric value is 0⁺,
+	and 0⁻ if A's numeric value is 0⁻.
 
 	Note: Both of these functions operate on the fully simplified/resolved form of their arguments,
 	which may give unintuitive results at first glance.