code: StringVector processPREFIX_URLLIST(
            StylesheetHandler handler, String uri, String name, String rawName, String value)
              throws org.xml.sax.SAXException
    {
  
      StringTokenizer tokenizer = new StringTokenizer(value, " \t\n\r\f");
      int nStrings = tokenizer.countTokens();
      StringVector strings = new StringVector(nStrings);
  
      for (int i = 0; i < nStrings; i++)
      {
        String prefix = tokenizer.nextToken();
        String url = handler.getNamespaceForPrefix(prefix);
  
        if (url != null)
          strings.addElement(url);
        else
          throw new org.xml.sax.SAXException(XSLMessages.createMessage(XSLTErrorResources.ER_CANT_RESOLVE_NSPREFIX, new Object[] {prefix}));
      
      }
  
      return strings;
    }
docs: Process an attribute string of type T_URLLIST into
  a vector of prefixes that may be resolved to URLs.
  
  @param handler non-null reference to current StylesheetHandler that is constructing the Templates.
  @param uri The Namespace URI, or an empty string.
  @param name The local name (without prefix), or empty string if not namespace processing.
  @param rawName The qualified name (with prefix).
  @param value A list of whitespace delimited prefixes.
  
  @return A vector of strings that may be resolved to URLs.
  
  @throws org.xml.sax.SAXException if one of the prefixes can not be resolved.