diff -r 80fa1401cf76 -r 4c98c929a12a NEWS
--- a/NEWS	Thu Sep 28 11:53:55 2017 +0200
+++ b/NEWS	Thu Sep 28 15:11:32 2017 +0200
@@ -7,6 +7,14 @@
 New in this Isabelle version
 ----------------------------
 
+*** General ***
+
+* Session-qualified theory names are mandatory: it is no longer possible
+to refer to unqualified theories from the parent session.
+INCOMPATIBILITY for old developments that have not been updated to
+Isabelle2017 yet (using the "isabelle imports" tool).
+
+
 *** HOL ***
 
 * SMT module: