diff --git a/docs/Documentation.xml b/docs/Documentation.xml
index 3bddc0c2d..47ecc4c76 100644
--- a/docs/Documentation.xml
+++ b/docs/Documentation.xml
@@ -1791,10 +1791,16 @@ ACCEPT<emphasis role="bold">:info</emphasis>   -              -               tc
           Variables</ulink> where a shell variable is set to "none" if a rule
           is to be omitted.</para>
 
-          <para>If the source is not <quote>all</quote> then the source may be
-          further restricted by adding a colon (<quote>:</quote>) followed by
-          a comma-separated list of qualifiers. Qualifiers are may
-          include:</para>
+          <para>"all" means "All Zones", including the firewall itself. "all-"
+          means "All Zones, except the firewall itself". When "all[-]" is used
+          either in the SOURCE or DEST column intra-zone traffic is not
+          affected. When "all+[-]" is used, intra-zone traffic is
+          affected.</para>
+
+          <para>If the source is not one of the variants of <quote>all</quote>
+          then the source may be further restricted by adding a colon
+          (<quote>:</quote>) followed by a comma-separated list of qualifiers.
+          Qualifiers are may include:</para>
 
           <variablelist>
             <varlistentry>