Index: trunk/BNS/bnshelp.html
===================================================================
--- trunk/BNS/bnshelp.html	(revision 2320)
+++ trunk/BNS/bnshelp.html	(revision 2321)
@@ -290,5 +290,5 @@
 </p>
 <p>
-Note that the '2nd order relativistic effect' is not used in BNS although it is required to provide it.
+Note that the '2nd order relativistic effect' is not used in BNS although it is required to provide it. If the relativistic effect is unavailable for you then you must at least send a dummy value.
 </p>