--- a/NEWS Fri Mar 05 17:02:32 2021 +0100
+++ b/NEWS Fri Mar 05 17:29:49 2021 +0100
@@ -7,6 +7,16 @@
New in this Isabelle version
----------------------------
+*** General ***
+
+* Timeouts for Isabelle/ML tools are subject to system option
+"timeout_scale" --- this already used for the overall session build
+process before, and allows to adapt to slow machines. The underlying
+Timeout.apply in Isabelle/ML treats an original timeout specification 0
+as no timeout; before it meant immediate timeout. Rare INCOMPATIBILITY
+in boundary cases.
+
+
*** HOL ***
* Theory Multiset: dedicated predicate "multiset" is gone, use