--- a/rdf-mt/index.html	Wed Apr 03 16:39:04 2013 -0700
+++ b/rdf-mt/index.html	Thu Apr 04 06:57:47 2013 -0700
@@ -482,7 +482,7 @@
 <p></p>
 </li></ul>
 
-<h3 id="D-entailment">Datatype entailment</h3>
+<h3 id="D_entailment">Datatype entailment</h3>
 
 <p>A graph is (simply) <dfn>D-satisfiable</dfn> when it has the value true in some D-interpretation, and a set S of graphs (simply) <dfn>D-entails</dfn> a graph G when every D-interpretation which makes S true also D-satisfies G.</p>