add note about transport matrix

diff --git a/en/manual.xml b/en/manual.xml
index 5a7db8b..e9bbfbc 100644 (file)
--- a/en/manual.xml
+++ b/en/manual.xml
@@ -16783,6 +16783,16 @@ location: [STAFF, ISO]</programlisting>Will block items with an itype code of
           </screenshot>
         <para>After entering in your cost, hit 'Enter' on your keyboard or click the 'Save' button
           at the bottom of the matrix to save your changes.</para>
+        <para>
+          <note>
+            <para>A NULL value will make no difference where the From and To libraries are the same
+              library. However, as a best practice, you should put a 0 in there. For all other
+              To/From combinations, a NULL value will cause that relationship to act as if it has
+              been disabled. So, in summary, don't leave any of the values empty. It's best to
+              always put a number in there ( even if you choose to disable that given To/From option
+              ).</para>
+          </note>
+        </para>
       </section>
       <section id="itemcircalerts">
         <title>Item Circulation Alerts</title>