[css-color-4] explicit xyz whitepoints, see #6722

css-color-4/Overview.bs

@@ -3834,12 +3834,15 @@ and ''xyz''.</h3>
 				rec2020-005.html
 			</wpt>
 
-		<dt><dfn>xyz</dfn>
+		<dt><dfn>xyz-d50</dfn>, <dfn>xyz-d65</dfn>, <dfn>xyz</dfn>
 			<dd>The ''xyz'' color space accepts three numeric parameters,
 				representing the X,Y and Z values.
 				It represents the CIE XYZ color space,
-				scaled such that diffuse white has a luminance (Y) of 1.0
-				and, if necessary, chromatically adapted to a [=D50=] reference white.
+				scaled such that diffuse white has a luminance (Y) of 1.0.
+				and, if necessary, chromatically adapted to the reference white.
+
+				The reference white for ''xyz-d50'' is [=D50=], while
+				the reference white for ''xyz-d65''  and ''xyz'' is [=D65=].
 
 				Values greater than 1.0 are allowed and must not be clamped;
 				they represent colors brighter than diffuse white.
@@ -3863,7 +3866,7 @@ and ''xyz''.</h3>
 						<span class="swatch" style="--color: #7654CD"></span> #7654CD
 						<span class="swatch" style="--color: #7654CD"></span> rgb(46.27% 32.94% 80.39%)
 						<span class="swatch" style="--color: #7654CD"></span> lab(44.36% 36.05 -58.99)
-						<span class="swatch" style="--color: #7654CD"></span> color(xyz 0.2005 0.14089 0.4472)
+						<span class="swatch" style="--color: #7654CD"></span> color(xyz-d50 0.2005 0.14089 0.4472)
 					</pre>
 				</div>