--- a/ttml10/spec/ttaf1-dfxp.xml	Sat May 25 20:30:17 2013 -0600
+++ b/ttml10/spec/ttaf1-dfxp.xml	Sun May 26 13:26:35 2013 -0600
@@ -4017,9 +4017,8 @@
 <p>If the value of this attribute consists of two <loc href="#style-value-length">&lt;length&gt;</loc>
 specifications, then they must be interpreted as <emph>width</emph>
 and <emph>height</emph>, where the first specification is the
-<emph>width</emph>, and the second specification is the
-<emph>height</emph>, where, if either <emph>width</emph> or <emph>height</emph> is negative or zero, then
-extent must be considered zero in both inline and block progression dimensions.</p>
+<emph>width</emph>, and the second specification is the <emph>height</emph>.</p>
+<p>The <loc href="#style-value-length">&lt;length&gt;</loc> value(s) used to express extent must be non-negative.</p>
 <p>If the value of this attribute is <code>auto</code>, then the initial value
 of the style property must be considered to be the same as the extent of the <emph>Root Container Region</emph>.</p>
 <p>