Add changes since 2015 CR

Author: svgeesus

compositing-1/Overview.bs

@@ -7,7 +7,7 @@ TR: https://www.w3.org/TR/compositing-1/
 Previous Version: https://www.w3.org/TR/2015/CR-compositing-1-20150113/
 Previous Version: https://www.w3.org/TR/2014/CR-compositing-1-20140220/
 Shortname: compositing
-Link Defaults: css-color-3 (property) color, svg (property) mask
+Link Defaults: css-color-4 (property) color, svg (property) mask
 Deadline: 2014-08-17
 Level: 1
 Group: fxtf
@@ -1415,6 +1415,19 @@ If this rule is not followed, an attacker could infer information and mount a ti
 
 <h2 id=changes>Changes</h2>
 
+The following changes were made relative to the <a
+href="https://www.w3.org/TR/2015/CR-compositing-1-20150113/"> Candidate Recommendation of 13 January 2015</a>:
+
+<ul>
+  <li>Defined root elements for HTML and SVG, and the root element group</li>
+  <li>Clarified that root groups are not necessarily opaque white</li>
+  <li>Better definitions for root group and isolating groups</li>
+  <li>Consistently use the multiplication symbol × rather than x or *</li>
+  <li>Corrected examples that used 'green' where 'lime' was meant</li>
+  <li>Corrected initial value of background-blend-mode </li>
+  <li>Assorted markup and linking fixes</li>
+</ul>
+
 The following changes were made relative to the <a
 href="https://www.w3.org/TR/2014/CR-compositing-1-20140220/"> Candidate Recommendation of 20 February 2014</a>:
 <ul>