diff -r d9343c0aac11 -r 11010e5f18f0 NEWS
--- a/NEWS	Wed Apr 15 15:52:37 2009 +0200
+++ b/NEWS	Thu Apr 16 10:11:34 2009 +0200
@@ -1,6 +1,14 @@
 Isabelle NEWS -- history user-relevant changes
 ==============================================
 
+*** HOL ***
+
+* Class semiring_div now requires no_zero_divisors and proof of div_mult_mult1;
+theorems div_mult_mult1, div_mult_mult2, div_mult_mult1_if, div_mult_mult1 and
+div_mult_mult2 have been generalized to class semiring_div, subsuming former
+theorems zdiv_zmult_zmult1, zdiv_zmult_zmult1_if, zdiv_zmult_zmult1 and zdiv_zmult_zmult2.
+div_mult_mult1 is now [simp] by default.  INCOMPATIBILITY.
+
 New in Isabelle2009 (April 2009)
 --------------------------------