diff --git a/reference/exec/reference.xml b/reference/exec/reference.xml
index f9ac7375d8..5c499a307e 100644
--- a/reference/exec/reference.xml
+++ b/reference/exec/reference.xml
@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="iso-8859-1"?>
-<!-- $Revision: 1.12 $ -->
+<!-- $Revision: 1.13 $ -->
 <!-- Purpose: fileprocess.process -->
 <!-- Membership: core -->
 
@@ -44,6 +44,16 @@
     &no.constants;
    </section>
 
+   <section xml:id="exec.notes">
+    &reftitle.notes;
+    <warning>
+     <para>
+      Open files with lock (especially open sessions) should be closed before
+      executing a program in the bacground.
+     </para>
+    </warning>
+   </section>
+
    <section xml:id="exec.seealso">
    &reftitle.seealso;
     <para>