diff --git a/docs/refguide.xml b/docs/refguide.xml
index 92ea03e9e..ea9d0e5d7 100644
--- a/docs/refguide.xml
+++ b/docs/refguide.xml
@@ -427,15 +427,13 @@ you would expect.</para>
           <emphasis>every</emphasis> target IP address specified.  So
           if a class B sized target address space (/16) is specified
           on the command line, all 65,536 IP addresses are scanned.
-          That second option character in <option>-PN</option> is a
-          zero and not the letter O.  Proper host discovery is skipped
-          as with the list scan, but instead of stopping and printing
-          the target list, Nmap continues to perform requested
-          functions as if each target IP is active.  For machines on a
-          local ethernet network, ARP scanning will still be performed
-          (unless <option>--send-ip</option> is specified) because
-          Nmap needs MAC addresses to further scan target
-          hosts.</para>
+          Proper host discovery is skipped as with the list scan, but
+          instead of stopping and printing the target list, Nmap
+          continues to perform requested functions as if each target
+          IP is active.  For machines on a local ethernet network, ARP
+          scanning will still be performed (unless
+          <option>--send-ip</option> is specified) because Nmap needs
+          MAC addresses to further scan target hosts.  This option flag for this used to be <option>P0</option> (uses zero), but was renamed to avoid confusion with protocol ping's <option>PO</option> (uses the letter O) flag.</para>
         </listitem>
       </varlistentry>