Please, I need help understanding the definition of these fields in the item_db_re table (mysql). I need to import yml to mysql, it's all done, but I don't understand the use of these fields, since they *when they exist in yml are of little clarity*, so, When will one of these fields be set to true?   `class_all` tinyint(1) unsigned DEFAULT NULL,   `class_normal` tinyint(1) unsigned DEFAULT NULL,   `class_upper` tinyint(1) unsigned DEFAULT NULL,   `class_baby` tinyint(1) unsigne