diff -r 2913a54e64cf -r c80aba8c1d5e src/Pure/Isar/args.ML
--- a/src/Pure/Isar/args.ML	Sun May 21 14:32:47 2000 +0200
+++ b/src/Pure/Isar/args.ML	Sun May 21 14:33:46 2000 +0200
@@ -181,7 +181,6 @@
   ((Scan.repeat1
     (Scan.repeat1 (atom_arg blk) ||
       paren_args "(" ")" args ||
-      paren_args "{" "}" args ||
       paren_args "[" "]" args)) >> flat) x;