update text in order to reflect that ZEXP is the official export/import format and

that XML export/import is partly broken

lib/python/OFS/dtml/importExport.dtml

@@ -10,6 +10,13 @@ them to a different Zope installation. You can either choose
 to download the export file to your local machine, or save it
 in the "var" directory of your Zope installation 
 on the server. 
+<br/>
+<b>Note:</b>
+Zope can export/import objects in two dfferent formats: a binary format (called
+ZEXP) and as XML. The ZEXP format is the officially supported export/import
+format if you want to use for moving data between identicial Zope
+installations. The XML export/import is unsupported (and maybe broken under
+certain circumstances. 
 </p>
 
 <form action="manage_exportObject" method="post">
@@ -46,7 +53,7 @@ on the server.
   </td>
   <td align="left" valign="top">
   <div class="form-text">
-  <input type="checkbox" name="toxml" value="Y" /> XML format?
+  <input type="checkbox" name="toxml" value="Y" /> XML format? (unsupported, see above)
   </div>
   </td>
 </tr>