Add note about comparing computed values.

Author: tabatkins

css3-values/Overview.src.html

@@ -1096,17 +1096,29 @@ <h3 id="toggle-notation">
 		Note that values with commas at the top-level
 		will be incorrectly interpreted as separate values.
 
-	<p>The value returned by ''toggle()'' must be determined by comparing
-	the inherited value <var>I</var> (the computed value on the parent,
-	or, for the root, the initial value) to the computed values
-	<var>C<sub>n</sub></var> returned by the <var>n</var>-th argument to
-	''toggle()''.
-	For the earliest <var>C<sub>n</sub></var> such that
-	<var>C<sub>n</sub></var> = <var>I</var>, the value returned by toggle
-	is <var>C<sub>n+1</sub></var>.  However, if this <var>C<sub>n</sub></var>
-	is the last value, or if there are no <var>C<sub>n</sub></var> that
-	equal <var>I</var>, the computed value of the first value is returned
-	instead.</p>
+	<p>
+		The value returned by ''toggle()'' must be determined 
+		by comparing the inherited value <var>I</var> 
+		(the computed value on the parent, 
+		or, for the root, the initial value) 
+		to the computed values <var>C<sub>n</sub></var> returned by the <var>n</var>-th argument to ''toggle()''.
+		For the earliest <var>C<sub>n</sub></var> 
+		such that <var>C<sub>n</sub></var> = <var>I</var>, 
+		the value returned by toggle is <var>C<sub>n+1</sub></var>.  
+		However, if this <var>C<sub>n</sub></var> is the last value, 
+		or if there are no <var>C<sub>n</sub></var> that equal <var>I</var>, 
+		the computed value of the first value is returned instead.
+
+	<p class='note'>
+		Note that "computed values" are abstract sets of values,
+		not particular serializations,
+		so comparison between computed values should always be unambiguous and have the expected result.
+		For example,
+		'box-shadow' computed values are just two offsets, a blur, a spread, and a color,
+		so the declarations ''box-shadow: 1px 1px blue;'' and ''box-shadow: 1px 1px 0px blue;''
+		produce identical computed values.
+		If the "Computed Value" line of a property definition seems to define something ambiguous or overly strict,
+		please <a href="#status">provide feedback</a> so we can fix it.
 
 	<p class='note'>Note that ''toggle()'' explicitly looks at the computed value
 	of the parent, so it is useful even for non-inherited properties.  This