private function determineSubTypeOfIndexedContainers($data) {
        list( $allNumeric, $inSequence ) = $this->detectContainerKeyFlags( $data );
        if( $allNumeric == false ){
            return "\xE2";
        }else if( $inSequence ){
            return "\xE0";
        }else{
            return "\xE1";
        }
    }