public static function construct($nwk_addr_of_interest, $endpoint)
 {
     $frame = new self();
     $frame->setNwkAddressOfInterest($nwk_addr_of_interest);
     $frame->setEndpoint($endpoint);
     return $frame;
 }
 public static function constructExtended($nwk_addr_of_interest, $endpoint, $start_index)
 {
     $frame = new self();
     $frame->setNwkAddressOfInterest($nwk_addr_of_interest);
     $frame->setEndpoint($endpoint);
     $frame->setStartIndex($start_index);
     return $frame;
 }