function CreateAxes($flags = 0)
 {
     $axes = new GRAPHAxes($this->req, $flags);
     $req = $this->srctree->GetSourceRequests();
     foreach ($req as $sreq) {
         $rdr = $this->CreateReader($sreq);
         $extra = $rdr->CreateExtraAxes();
         if ($extra) {
             $axes->Add($extra);
         }
     }
     return $axes;
 }