[css-color-4] Define and export term "modern color syntax"

Author: Chris Lilley

css-color-4/Overview.bs

@@ -131,7 +131,7 @@ div.example {
 	overflow: visible;
 }
 div.example>a.self-link::before {
-    content: "¶";
+	content: "¶";
 }
 </style>
 
@@ -881,21 +881,27 @@ Representing Colors: the <<color>> type</h2>
 	are [=cylindrical polar color=] representations using a <<hue>> angle;
 	the other [=color functions=] use [=rectangular orthogonal color=] representations.
 
+<h4 id="color-syntax-modern">
+Modern (Space-separated) Color Function Syntax</h4>
+
 	All of the <<absolute-color-function>> syntactic forms
 	defined in this specification
-	use space, not comma,
-	to separate the color components.
-	They also use a solidus ("/")
-	to separate an optional alpha term
-	from the color components.
+	use the <dfn export>modern color syntax</dfn>,
+	meaning: 
+	
+	* color components are separated by whitespace
+	* the optional alpha term is separated by a solidus ("/")
+	* minimum required precision <a href="#serializing-color-values">when serializing</a> is defined,
+		and may be greater than 8 bits per component
+	* the ''none'' value is allowed, to represent [=missing components=]
 
-	<div class=example id="example-generic-syntax">
+	<div class=example id="example-modern-syntax">
 		<p>The following represents a saturated sRGB red that is 50% opaque:
 		<pre>rgb(100% 0% 0% / 50%)</pre>
 	</div>
 
 <h4 id="color-syntax-legacy">
-Legacy Comma-separated Color Function Syntax</h4>
+Legacy (Comma-separated) Color Function Syntax</h4>
 
 	For Web compatibility,
 	the syntactic forms
@@ -910,6 +916,8 @@ Legacy Comma-separated Color Function Syntax</h4>
 		(optionally preceded and/or followed by whitespace)
 	* non-opaque forms use a separate notation
 		(for example ''hsla()'' rather than ''hsl()'')
+		and the alpha term is separated by  commas
+		(optionally preceded and/or followed by whitespace)
 	* minimum required precision is lower, 8 bits per component
 	* the ''none'' value is not allowed