diff -r a1b2ea991ad1 -r e32750d7acb4 NEWS
--- a/NEWS	Mon Oct 02 18:35:51 2017 +0200
+++ b/NEWS	Mon Oct 02 19:28:18 2017 +0200
@@ -14,6 +14,10 @@
 INCOMPATIBILITY for old developments that have not been updated to
 Isabelle2017 yet (using the "isabelle imports" tool).
 
+* Command 'external_file' declares the formal dependency on the given
+file name, such that the Isabelle build process knows about it, but
+without specific Prover IDE management.
+
 
 *** HOL ***