diff -r 560fbd6bc047 -r 1d005f514417 NEWS
--- a/NEWS	Thu Feb 15 13:04:36 2018 +0100
+++ b/NEWS	Fri Feb 16 10:59:14 2018 +0100
@@ -210,6 +210,9 @@
 * Predicate pairwise_coprime abolished, use "pairwise coprime" instead.
 INCOMPATIBILITY.
 
+* The relator rel_filter on filters has been strengthened to its 
+canonical categorical definition with better properties. INCOMPATIBILITY.
+
 * HOL-Algebra: renamed (^) to [^]
 
 * Session HOL-Analysis: Moebius functions and the Riemann mapping