public static function block_tags( $reset = false ) {
		if ( empty( self::$block_tags ) || $reset ) {
			self::$block_tags = \array_merge(
				\array_flip(
					\array_filter(
						\array_keys( Elements::$html5 ),
						function( $tag ) {
							return Elements::isA( $tag, Elements::BLOCK_TAG );
						}
					)
				),
				\array_flip( [ 'li', 'td', 'dt' ] ) // not included as "block tags" in current HTML5-PHP version.
			);
		}

		return self::$block_tags;
	}