From PHPBB用户手册

# Table: 'phpbb_extensions'
CREATE TABLE phpbb_extensions (
	extension_id mediumint(8) UNSIGNED NOT NULL auto_increment, 扩展名ID
	group_id mediumint(8) UNSIGNED DEFAULT '0' NOT NULL, 隶属于的扩展名组ID
	extension varchar(100) DEFAULT '' NOT NULL, 扩展名
	PRIMARY KEY (extension_id)
) CHARACTER SET `utf8` COLLATE `utf8_bin`;