public function unknown_assoc( $assoc_args ) {
		$generic = $this->query_spec(
			array(
				'type' => 'generic',
			)
		);

		if ( count( $generic ) ) {
			return array();
		}

		$known_assoc = array();

		foreach ( $this->spec as $param ) {
			if ( in_array( $param['type'], array( 'assoc', 'flag' ), true ) ) {
				$known_assoc[] = $param['name'];
			}
		}

		return array_diff( array_keys( $assoc_args ), $known_assoc );
	}