--- a/src/ZF/upair.thy Sun Nov 02 16:09:35 2014 +0100
+++ b/src/ZF/upair.thy Sun Nov 02 16:39:54 2014 +0100
@@ -9,7 +9,7 @@
Ordered pairs and descriptions are defined using cons ("set notation")
*)
-header{*Unordered Pairs*}
+section{*Unordered Pairs*}
theory upair
imports ZF