NEWS

--- a/NEWS	Mon Jan 04 19:56:33 2021 +0100
+++ b/NEWS	Mon Jan 04 19:41:38 2021 +0100
@@ -162,6 +162,9 @@
 * Library theory "Signed_Division" provides operations for signed
 division, instantiated for type int.
 
+* Theory "Multiset": removed misleading notation \<Union># for sum_mset;
+replaced with \<Sum>\<^sub>#.
+
 * Self-contained library theory "Word" taken over from former session
 "HOL-Word".