diff -r 9537bf1c4853 -r 5b7a9633cfa8 src/HOL/ex/BT.thy
--- a/src/HOL/ex/BT.thy	Sun Nov 02 18:21:14 2014 +0100
+++ b/src/HOL/ex/BT.thy	Sun Nov 02 18:21:45 2014 +0100
@@ -5,7 +5,7 @@
 Binary trees
 *)
 
-header {* Binary trees *}
+section {* Binary trees *}
 
 theory BT imports Main begin