After a bit of research, I've figured out how to parse xml using Oracle9i. The process is a bit more involved than Oracle8i but there is more functionality. The following bit of PL/SQL code will parse the following XML:

<r session="sess01" updator="medined" object="1005769145473">
 <f n="PMA_APPROVAL_MEANS" v="Identicality Per FAR 21.303(c)"/>
</r>

You'll need to place the following code into context that makes sense for your projects, but here is the gist:

-- declare attributes
p          xmlparser.Parser;
doc        xmldom.DOMDocument;
element    xmldom.DOMElement;
facts      xmldom.DOMNodeList;
node       xmldom.DOMNode;
attributes xmldom.DOMNamedNodeMap;

-- parse the xml packet
p := xmlparser.newParser;
xmlparser.setValidationMode(p, FALSE);
xmlparser.parseBuffer(p, v_xml_packet);
doc  := xmlparser.getDocument(p);

BEGIN
  element := xmldom.getDocumentElement(doc);
EXCEPTION
  RAISE;
END;

v_session := xmldom.getAttribute(element, 'session');
v_updator := xmldom.getAttribute(element, 'updator');
v_object  := xmldom.getAttribute(element, 'object');

facts := xmldom.getChildrenByTagName( element, 'f');
FOR j IN 1..xmldom.getLength(facts) LOOP

        node := xmldom.item(facts, j-1);
        attributes := xmldom.getAttributes(node);

        if (xmldom.isNull(attributes) = FALSE) then
          num_attributes := xmldom.getLength(attributes);

          -- loop through attributes
          for i in 0..num_attributes-1 loop
             node := xmldom.item(attributes, i);
             attribute_name := xmldom.getNodeName(node);
             if attribute_name = 'n' then
                 v_fact_name := xmldom.getNodeValue(node);
             end if;
             if attribute_name = 'v' then
                 v_fact_value := xmldom.getNodeValue(node);
             end if;
          end loop;

          ---- do some processing here.

       end if;
END LOOP;

UNSPSC codes are four sets of two characters.

Each pair of character helps to define a category in a hierarchical manner. So the left pairs (like 10 00 00 00) define a very broad category while the right pairs (like 11 23 44 02) defines a very narrow category. Giving any category code, you can find its parent category code via the following java code:

// Move the unspsc code into a stringbuffer so it can be manipulated
StringBuffer uc = new StringBuffer(unspsc_code);

// replace digits 7 & 8 with zeros.
// if code has changed then that's the parent category
// The setCharAt function uses a zero-based index.So the
// range is 0 to 7 instead of 1 to 8.
uc.setCharAt(7, '0');
uc.setCharAt(6, '0');

if (! unspsc_code.equals(uc.toString())) {
  System.out.println(uc + " is the parent category");
}
else {
  // replace digits 5 & 6 with zeros.
  uc.setCharAt(5, '0');
  uc.setCharAt(4, '0');
  if (! unspsc_code.equals(uc.toString())) {
    System.out.println(uc + " is the parent category");
  }
  else {
    // replace digits 3 & 4 with zeros.
    uc.setCharAt(3, '0');
    uc.setCharAt(2, '0');
    if (! unspsc_code.equals(uc.toString())) {
      System.out.println(uc + " is the parent category");
    }
    else {
      System.out.println(uc + " is a top-level category.");
    }
  }
}