[css3-fonts] allow user agents to synthesize kern feature from kern table data

Author: John Daggett

css-fonts/Fonts.html

@@ -115,15 +115,15 @@
 
    <h1>CSS Fonts Module Level 3</h1>
 
-   <h2 class="no-num no-toc" id=editors-draft-19-august-2013>Editor's Draft
-    19 August 2013</h2>
+   <h2 class="no-num no-toc" id=editors-draft-26-august-2013>Editor's Draft
+    26 August 2013</h2>
 
    <dl id=authors>
     <dt>This version:
 
     <dd><a
      href="http://dev.w3.org/csswg/css-fonts/">http://dev.w3.org/csswg/css-fonts/</a>
-     <!-- <dd><a href="http://www.w3.org/TR/2013/ED-css-fonts-3-20130819/">http://www.w3.org/TR/2013/ED-css-fonts-3-20130819/</a>  -->
+     <!-- <dd><a href="http://www.w3.org/TR/2013/ED-css-fonts-3-20130826/">http://www.w3.org/TR/2013/ED-css-fonts-3-20130826/</a>  -->
 
 
     <dt>Latest version:
@@ -5293,17 +5293,20 @@ <h3 id=font-feature-settings-prop><span class=secno>6.12 </span>Low-level
    rules</a> defined in the OpenType specification <a
    href="#OPENTYPE-FEATURES"
    rel=biblioentry>[OPENTYPE-FEATURES]<!--{{!OPENTYPE-FEATURES}}--></a>.
-   Feature tags not present in the font are ignored; a user agent must not
-   attempt to synthesize fallback behavior based on these feature tags.
-
-  <p>This means that explicitly disabling the <span class=tag>kern</span>
-   feature will not affect the application of kerning data found in the
-   ‘<code class=property>kern</code>’ table (as opposed to kerning data
-   associated with the <span class=tag>kern</span> feature in the ‘<code
-   class=property>GPOS</code>’ table). Authors should use the ‘<a
+
+  <p>Feature tags not present in the font are ignored; a user agent must not
+   attempt to synthesize fallback behavior based on these feature tags. The
+   one exception is that user agents may synthetically support the <span
+   class=tag>kern</span> feature with fonts that contain kerning data in the
+   form of a ‘<code class=property>kern</code>’ table but lack <span
+   class=tag>kern</span> feature support in the ‘<code
+   class=property>GPOS</code>’ table.
+
+  <p class=note>In general, authors should use the ‘<a
    href="#propdef-font-kerning"><code
-   class=property>font-kerning</code></a>’ property to explictly enable or
-   disable kerning since this property affects both types of kerning.
+   class=property>font-kerning</code></a>’ property to explicitly enable or
+   disable kerning since this property always affects fonts with either type
+   of kerning data.
 
   <p>If present, a value indicates an index used for glyph selection. An
    &lt;integer&gt; value must be 0 or greater. A value of 0 indicates that