Documentation just says about severities but does not describe numeric -> text representation:
define('ITEM_LOGTYPE_INFORMATION', 1);
define('ITEM_LOGTYPE_WARNING', 2);
define('ITEM_LOGTYPE_ERROR', 4);
define('ITEM_LOGTYPE_FAILURE_AUDIT', 7);
define('ITEM_LOGTYPE_SUCCESS_AUDIT', 8);
define('ITEM_LOGTYPE_CRITICAL', 9);
define('ITEM_LOGTYPE_VERBOSE', 10);