--- a/master/definitions.xml	Thu Feb 07 09:26:04 2013 +1100
+++ b/master/definitions.xml	Tue Mar 05 15:54:18 2013 +1100
@@ -1057,6 +1057,7 @@
   <interface name='SVGDefsElement' href='struct.html#InterfaceSVGDefsElement'/>
   <interface name='SVGTitleElement' href='struct.html#InterfaceSVGTitleElement'/>
   <interface name='SVGDescElement' href='struct.html#InterfaceSVGDescElement'/>
+  <interface name='SVGDiscardeElement' href='struct.html#InterfaceSVGDescElement'/>
   <interface name='SVGSymbolElement' href='struct.html#InterfaceSVGSymbolElement'/>
   <interface name='SVGUseElement' href='struct.html#InterfaceSVGUseElement'/>
   <interface name='SVGPathElement' href='paths.html#InterfaceSVGPathElement'/>
@@ -1389,6 +1390,11 @@
   <term name='InvalidStateError' href='http://www.w3.org/TR/2012/WD-dom-20120405/#invalidstateerror'/>
   <term name='SyntaxError' href='http://www.w3.org/TR/2012/WD-dom-20120405/#syntaxerror'/>
 
+  <term name='compositing group' href='http://www.w3.org/TR/compositing/#groups'/>
+  <term name='group backdrop' href='http://www.w3.org/TR/compositing/#groups'/>
+  <term name='knock-out' href='http://www.w3.org/TR/compositing/#knock-out'/>
+  <term name='isolation' href='http://www.w3.org/TR/compositing/#enable-background'/>
+
   <!-- ... grammar symbols ................................................ -->
   <symbol name='angle' href='http://www.w3.org/TR/2012/WD-css3-values-20120308/#angles'/>
   <symbol name='identifier' href='http://www.w3.org/TR/2012/WD-css3-values-20120308/#identifier'/>

--- a/master/render.html	Thu Feb 07 09:26:04 2013 +1100
+++ b/master/render.html	Tue Mar 05 15:54:18 2013 +1100
@@ -70,10 +70,16 @@
 
 <p>SVG uses a "painters model" of rendering. <a>Paint</a>
 is applied in successive operations to the output device such
-that each operation paints over some area of the output device.
-The first layer is always the background canvas. The background color of this canvas is defined by the <a>'viewport-fill'</a> property.
-As successive objects and group are painted onto the background, they are composited following the rules of the <a href="http://www.w3.org/TR/compositing/">Compositing and Blending Specification</a>.
-After each object or group is painted, it becomes part of the background for the next painting operation.
+that each operation paints onto some area of the output device,
+possibly obscuring paint that has previously been layed down.
+
+After each object or group is painted, it becomes part of the background
+for the next painting operation.
+
+SVG 2 supports advanced blending modes and compositing operations that
+control how each painting operation interacts with the background.
+The rules governing these painting operations are outlined in the
+<a href="http://www.w3.org/TR/compositing/">Compositing and Blending Specification</a>.
 </p>
 </div>
 
@@ -97,7 +103,7 @@
 <div class="ready-for-wg-review">
 <p>
 Individual <a>graphics elements</a> are rendered as if each graphics element
-represented its own <a>compositing group</a>; thus, the effect is as if 
+represented its own <a>compositing group</a>; thus, the effect is as if
 a temporary separate canvas is created for each graphics element.
 The element is first painted onto the temporary canvas (see
 <a href="render.html#PaintingShapesAndText">Painting shapes and text</a> and
@@ -182,6 +188,8 @@
 
 <div class="issue">
     This section needs more detail on the interaction between compositing and blending and filter effects.
+    Waiting on the Compositing and Blending spec to define the accumulated background removal process.
+    Filtering will need to fit into that process as the final step before the group buffer is composited with the page.
 </div>
 
 <p>SVG allows any painting operation to be filtered. (See
@@ -222,8 +230,8 @@
 channel in a referenced SVG element to define a supplemental
 set of alpha values which are multiplied to the alpha values
 already present in the graphics to which the mask is applied.
-The resulting alpha value is used as input to the Compositing 
-and Blending operations described in the <a href="http://www.w3.org/TR/compositing/">Compositing and Blending Specification</a>. 
+The resulting alpha value is used as input to the Compositing
+and Blending operations described in the <a href="http://www.w3.org/TR/compositing/">Compositing and Blending Specification</a>.
 Masking is described in detail in <a href="masking.html#Masking">Masking</a>.</p>
 
 <p>A supplemental masking operation may also be specified by