diff -r 2e9bf718a7a1 -r 65631ca437c9 src/FOL/ex/Nat.thy
--- a/src/FOL/ex/Nat.thy	Mon Dec 20 15:24:25 2010 +0100
+++ b/src/FOL/ex/Nat.thy	Mon Dec 20 16:44:33 2010 +0100
@@ -13,7 +13,7 @@
 arities nat :: "term"
 
 consts
-  0 :: nat    ("0")
+  Zero :: nat    ("0")
   Suc :: "nat => nat"
   rec :: "[nat, 'a, [nat, 'a] => 'a] => 'a"
   add :: "[nat, nat] => nat"    (infixl "+" 60)