[css-color-4] out of range values for profiled colors, w3c#3845

Author: svgeesus

css-color-4/Overview.bs

@@ -2550,6 +2550,23 @@ Profiled, Device-dependent Colors</h2>
 		<dl class=switch>
 			<dt>If the colorspace takes numeric parameters
 			<dd>
+
+				For custom colorspaces,
+				specified component values
+				less than 0 or 0%, or greater than 1 or 100%
+				are not invalid;
+				they are clamped to the valid range at computed value time.
+				This is because ICC profiles typically do not accept
+				out of range input values.
+
+				For predefined colorspaces,
+				specified component values
+				less than 0 or 0%, or greater than 1 or 100%
+				are not invalid;
+				these out of gamut colors
+				are gamut mapped to the valid range at computed value time,
+				with a relative colorimetric intent.
+
 				If more <<number>>s or <<percentage>>s are provided than parameters that the colorspace takes,
 				the excess <<number>>s at the end are ignored.
 				The color is still a [=valid color=].