diff -r b9556a055632 -r 6e2010ab8bd9 src/HOL/Isar_Examples/Summation.thy
--- a/src/HOL/Isar_Examples/Summation.thy	Sun Nov 02 17:20:45 2014 +0100
+++ b/src/HOL/Isar_Examples/Summation.thy	Sun Nov 02 17:23:48 2014 +0100
@@ -2,7 +2,7 @@
     Author:     Markus Wenzel
 *)
 
-header \<open>Summing natural numbers\<close>
+section \<open>Summing natural numbers\<close>
 
 theory Summation
 imports Main