--- a/src/ZF/Sum.thy Sun Nov 02 16:09:35 2014 +0100
+++ b/src/ZF/Sum.thy Sun Nov 02 16:39:54 2014 +0100
@@ -3,7 +3,7 @@
Copyright 1993 University of Cambridge
*)
-header{*Disjoint Sums*}
+section{*Disjoint Sums*}
theory Sum imports Bool equalities begin