--- a/ttml10-sdp-us/sdp-us.xml	Wed May 08 16:05:29 2013 -0600
+++ b/ttml10-sdp-us/sdp-us.xml	Wed May 08 16:17:32 2013 -0600
@@ -18,6 +18,7 @@
     <feature value="required">#layout</feature>
     <feature value="required">#length-percentage</feature>
     <feature value="required">#length-positive</feature>
+    <feature value="required">#length-real</feature>
     <feature value="required">#lineBreak-uax14</feature>
     <feature value="required">#presentation</feature>
     <feature value="required">#profile</feature>