[css-color-4] Interpolation is the most common situation which combines two colors, but not the only one. w3c#10151

Author: svgeesus

css-color-4/Overview.bs

@@ -1106,7 +1106,9 @@ any achromatic color will have a [=powerless=] hue component.
 		parsing/color-valid-rgb.html
 	</wpt>
 
-	For handling of [=missing component=] in color interpolation,
+	For handling of [=missing components=] in 
+	situations which combine two colors,
+	such as color interpolation,
 	see [[#interpolation-missing]].
 
 	For all other purposes, a [=missing component=] behaves as a zero value,