--- a/NEWS Fri May 01 11:22:09 1998 +0200
+++ b/NEWS Fri May 01 11:23:04 1998 +0200
@@ -96,6 +96,9 @@
* many new identities for unions, intersections, set difference, etc.;
+*** ZF ***
+
+* in let x=t in u(x), neither t nor u(x) has to be an FOL term.
New in Isabelle98 (January 1998)