How to format RDQL query? (using class_RDQL)

[Howard Lindsay]

I want to query the ODP data from Dmoz (which is an RDF document) using RDQL. Like this example:
http://dmoz.org/rdf/content.example.txt
I want to pick up the url, title and description from each of the external page entities which look like this:
<ExternalPage about="http://store.yahoo.com/attivousa">
  <d:Title>Attivo</d:Title>
  <d:Description>Bikinis briefs from top designers.</d:Description>
</ExternalPage>

The url is an attribute of the ExternalPage tag ('about'). I don't know how to format my query to get all three items. Can anyone help?

Here is what I have:

<?php

include_once("class_rdql.php");

print("<h1>RDQL test</h1><br/>\n");
$query[0]='SELECT ?sal, ?x
FROM    <content.rdf>
WHERE    (?x, <d:Title>, ?y),
        (?y, <d:Description>, ?sal)
USING d for <http://purl.org/dc/elements/1.0#>';
/*
$query[1]='SELECT ?sal, ?t, ?x
FROM    <http://ilrt.org/discovery/2000/11/rss-query/jobs-rss.rdf>,
    <http://ilrt.org/discovery/2000/11/rss-query/jobs.rss>
WHERE    (?x, <job:advertises>, ?y),
    (?y, <job:salary>, ?sal),
    (?y, <job:title>, ?t)
AND    (?sal >= 100000)
USING job for <http://ilrt.org/discovery/2000/11/rss-query/jobvocab.rdf#>';
*/

foreach($query as $a_query) {
  $head=false;
  $rows = RDQL_query_document::rdql_query_url($a_query);
  print("<table border='1' width='80%'>");
  print("<tr><td bgcolor='#aaaacc'>Query:</td></tr>");
  $a_query=str_replace("<","&lt;",$a_query);
  $a_query=str_replace(">","&gt;",$a_query);
  print("<tr><td bgcolor='#ccccee'><pre>$a_query</pre></td></tr>");
  print("</table>");
  print("<b>Result:</b>");
  print("<table border='1'width='80%'>");
  foreach($rows as $row) {
    if(!$head) {
      print("<tr>");
      foreach(array_keys($row) as $k) {
        print("<td bgcolor='#bbbbbb'><b>$k</b></td>");
      }
      print("</tr>");
      $head=true;
    }
    print("<tr>");
    foreach($row as $key=>$val) {
      print("<td bgcolor='#dddddd'>$val</td>");
    }
    print("</tr>");
  }
  print("</table>");
  print("<br/>");
}

?>