diff -r 8531c18d9181 -r 8cd9cfc22dd7 src/Pure/Interface/proof_general.ML
--- a/src/Pure/Interface/proof_general.ML	Thu Aug 03 18:44:24 2000 +0200
+++ b/src/Pure/Interface/proof_general.ML	Thu Aug 03 18:44:55 2000 +0200
@@ -212,7 +212,7 @@
     (Scan.succeed (Toplevel.no_timing o IsarCmd.undo));
 
 val undoP =
-  OuterSyntax.improper_command "ProofGeneral.undo" "undo last command (no output)" K.control
+  OuterSyntax.improper_command "ProofGeneral.undo" "(internal)" K.control
     (Scan.succeed (Toplevel.no_timing o IsarCmd.undo));
 
 val context_thy_onlyP =