[css-color-4] greater clarity on non-existence

Author: svgeesus

css-color-4/Overview.bs

@@ -2300,7 +2300,7 @@ Profiled, Device-dependent Colors</h2>
 
 	The ''color()'' function allows a color to be specified
 	in a particular [=colorspace=]
-	(rather than the implicit sRGB colorspace that the other color functions operate in).
+	(rather than the implicit sRGB colorspace that most of the other color functions operate in).
 	Its syntax is:
 
 	<pre class='prod'>
@@ -2315,15 +2315,24 @@ Profiled, Device-dependent Colors</h2>
 	Each argument has the following form:
 
 	* An optional <<ident>>  or <<dashed-ident>> denoting the colorspace.
-		If this is an <<ident>> it denotes one of the predefined colorspaces
+		If this is an <<ident>> it denotes one of the <a href="#predefined">predefined colorspaces</a>
 		(such as ''display-p3'');
 		if it is a <<dashed-ident>> it denotes a custom
 		colorspace, defined by a ''@color-profile'' rule.
 		If omitted, it defaults to the predefined ''srgb'' color profile.
 
-		If the <<ident>> or <<dashed-ident>> names a non-existent colorspace,
+		If the <<ident>> names a non-existent colorspace
+		(a name that does not match one of the <a href="#predefined">predefined colorspaces</a>),
+		or a predefined but unsupprted colorspace,
 		this argument represents an <a>invalid color</a>.
 
+		If the <<dashed-ident>> names a non-existent colorspace
+		( a name that does not match an <a>color profile's</a> name,
+		  or which matches but the corresponding profile has not loaded,
+		  or does not represent a valid profile),
+		this argument represents an <a>invalid color</a>.
+
+
 	* Either one or more <<number>>s or <<percentage>>s providing the parameter values that the colorspace takes,
 		or a <<string>> giving the name of a color defined by the colorspace.