diff -r fae6051ec192 -r 9bc3b57c1fa7 NEWS
--- a/NEWS	Sun Apr 09 19:56:52 2017 +0200
+++ b/NEWS	Sun Apr 09 20:17:00 2017 +0200
@@ -166,6 +166,14 @@
 ISABELLE_PLATFORM64.
 
 
+*** System ***
+
+* System option "record_proofs" allows to change the global
+Proofterm.proofs variable for a session. Regular values are are 0, 1, 2;
+a negative value means the current state in the ML heap image remains
+unchanged.
+
+
 
 New in Isabelle2016-1 (December 2016)
 -------------------------------------