src/HOL/Library/Product_plus.thy

--- a/src/HOL/Library/Product_plus.thy	Sun Nov 02 17:16:01 2014 +0100
+++ b/src/HOL/Library/Product_plus.thy	Sun Nov 02 17:20:45 2014 +0100
@@ -2,7 +2,7 @@
     Author:     Brian Huffman
 *)
 
-header {* Additive group operations on product types *}
+section {* Additive group operations on product types *}
 
 theory Product_plus
 imports Main