--- a/ttml2/spec/ttml2.xml	Fri Aug 09 10:33:45 2013 -0600
+++ b/ttml2/spec/ttml2.xml	Tue Aug 20 09:48:31 2013 -0600
@@ -1746,7 +1746,7 @@
 may be supported by a <emph>Content Processor</emph> in order to process a
 <emph>Document Instance</emph> that makes (or may make) use of such features and
 extensions. In addition, a feature or extension may be specified as
-prohibited, in which case it must not appear in or be used by
+prohibited, in which case it must not appear (be specified) in
 a <emph>Document Instance</emph>, and, if it does appear, may result in
 the <emph>Document Instance</emph> being rejected or processing otherwise aborted.</p>
 <note role="clarification">
@@ -1987,7 +1987,7 @@
 <code>use</code>, then the processor must both (1) implement or
 otherwise support the feature and (2) have enabled (activated) use of the
 feature; if the value is <code>prohibited</code>, then the document must not
-include or otherwise use the feature, and, if it does, then the processor
+include or otherwise specify any use of the feature, and, if it does, then the processor
 should reject or abort processing of the document.</p>
 <note role="clarification">
 <p>The default value of the <att>value</att> attribute is
@@ -1996,7 +1996,11 @@
 specified on a <el>ttp:feature</el> element, it is equivalent to
 specifying that support for the feature is required.</p>
 </note>
-
+<note role="clarification">
+<p>Use of the <code>prohibited</code> value for a feature value is not to be
+interpreted as meaning that a conformant processor need not or must not support
+the default semantics that apply for that feature.</p>
+</note>
 <p>If the value of the <att>value</att> attribute is
 <code>required</code> or <code>use</code>
 and the TTML processor implementation does