--- a/master/masking.html	Tue Jul 31 15:59:28 2012 +0900
+++ b/master/masking.html	Tue Jul 31 15:59:28 2012 +0900
@@ -616,6 +616,11 @@
   </dd>
 </dl>
 
+<div class="issue">
+  This should probably allow a CSS &lt;gradient&gt;, or, even better,
+  a CSS &lt;image&gt;.
+</div>
+
 <p>
 The meaning of the different <a>&lt;mask-source&gt;</a> values is as follows:
 </p>
@@ -675,6 +680,9 @@
   attribute on the <a>'mask element'</a> element.
   Otherwise, the alpha values of the mask source should be used as the 
   mask values.
+  <p class="issue">
+    Should the default be <span class="prop-value">luminance</span> instead?
+  </p>
   </dd>
 </dl>