--- a/ttml2/spec/ttml2.xml	Thu Apr 24 12:10:30 2014 -0600
+++ b/ttml2/spec/ttml2.xml	Thu Apr 24 12:53:45 2014 -0600
@@ -3133,7 +3133,7 @@
 <note role="explanation">
 <p>When the time base is designated as <code>smpte</code>,
 every time expression denotes a media marker value akin to that
-defined by <bibref ref="smil3"/>, &sect; 5.4.1, except instead
+defined by <bibref ref="smil3"/>, &sect; 5.4.3, except instead
 of using an opaque marker name, a structured <bibref ref="smpte12m"/>
 time coordinate serves as the marker name.</p>
 </note>
@@ -8607,7 +8607,7 @@
 <p>The begin point of a temporal interval is included in the
 interval; i.e., the interval is left-wise closed.</p>
 <p>The semantics of the <att>begin</att> attribute are those defined
-by <bibref ref="smil3"/>, &sect; 5.4.1,
+by <bibref ref="smil3"/>, &sect; 5.4.3,
 while taking into account any overriding semantics defined by this specification.</p>
 </div3>
 <div3 id="timing-attribute-end">
@@ -8631,7 +8631,7 @@
 as [300f,310f).</p>
 </note>
 <p>The semantics of the <att>end</att> attribute are those defined
-by <bibref ref="smil3"/>, &sect; 5.4.1,
+by <bibref ref="smil3"/>, &sect; 5.4.3,
 while taking into account any overriding semantics defined by this specification.</p>
 </div3>
 <div3 id="timing-attribute-dur">
@@ -8651,8 +8651,10 @@
 mode, a (well-formed) <att>dur</att> attribute must not be specified on any
 element.</p>
 <p>The semantics of the <att>dur</att> attribute are those defined
-by <bibref ref="smil3"/>, &sect; 5.4.1,
-while taking into account any overriding semantics defined by this specification.</p>
+by <bibref ref="smil3"/>, &sect; 5.4.3,
+while taking into account any overriding semantics defined by this specification.
+In a willful violation of <bibref ref="smil3"/>, &sect; 5.4.3, the value of
+the <att>dur</att> attribute is permitted to be zero (0).</p>
 <note role="elaboration">
 <p>In the context of the subset of <bibref ref="smil3"/> semantics supported by
 this specification, the active duration of an element that specifies both
@@ -8703,7 +8705,7 @@
 <item><p><loc href="#content-vocabulary-span"><el>span</el></loc></p></item>
 </ulist>
 <p>The semantics of parallel and sequential time
-containment are those defined by <bibref ref="smil3"/>, &sect; 5.4.2,
+containment are those defined by <bibref ref="smil3"/>, &sect; 5.4.4,
 while taking into account any overriding semantics defined by this specification.</p>
 </div3>
 </div2>