diff -r b89462f9d5f1 -r ec86863e87c8 src/ZF/ex/BT.thy
--- a/src/ZF/ex/BT.thy	Mon Nov 28 19:48:30 1994 +0100
+++ b/src/ZF/ex/BT.thy	Tue Nov 29 00:31:31 1994 +0100
@@ -18,7 +18,7 @@
 datatype
   "bt(A)" = Lf  |  Br ("a: A",  "t1: bt(A)",  "t2: bt(A)")
   
-rules
+defs
   bt_rec_def
     "bt_rec(t,c,h) == Vrec(t, %t g.bt_case(c, %x y z. h(x,y,z,g`y,g`z), t))"