--- a/ttml10-sdp-us/Overview.html	Mon Sep 24 11:32:34 2012 +0800
+++ b/ttml10-sdp-us/Overview.html	Tue Sep 25 09:59:38 2012 +0800
@@ -409,7 +409,7 @@
 <span style="color: blue;">&lt;</span><span style="color: #a31515;">span</span><span style="color: blue;"> </span><span style="color: red;">style</span><span style="color: blue;">=</span>"<span style="color: blue;">s1</span>"<span style="color: blue;">&gt;</span>C<span style="color: blue;">&lt;/</span><span style="color: #a31515;">span</span><span style="color: blue;">&gt;</span>
 </pre>
 <p data-transform='constraint'>A document MUST reference all styles using a style attribute to a style element.</p>
-<p data-transform='constraint'>A document MUST have all elements are in order of time. That is, in a par context, no element shall lexically precede another element with an earlier start time.</p>
+<p data-transform='constraint'>A document MUST have all elements are in order of time. That is, in a par context, an element MUST NOT lexically precede another element with an earlier start time.</p>
 </section>
 <section id='Constrained_Features'>
 <h2>Constrained Features</h2>
@@ -1363,7 +1363,7 @@
 </pre>
 <p data-transform='constraint'>For timing in hh:mm:ss.ms, the following format MUST be used:</p>
 <ul>
-<li>Exactly 2 digits SHALL be used in each of the hours, minutes, second, and frame components (include leading zeros).</li>
+<li>Exactly 2 digits MUST be used in each of the hours, minutes, second, and frame components (include leading zeros).</li>
 <li>A ttp:frameRate attribute MUST be present on the root element.</li>
 <li>A ttp:frameRateMultiplier attribute MAY be present on the root element.</li>
 </ul>