In the macro {ITEM.LOG.SEVERITY}, the value "critical" is expanded to "unknown".

const char	*zbx_item_logtype_string(unsigned char logtype)
{
	switch (logtype)
	{
		case ITEM_LOGTYPE_INFORMATION:
			return "Information";
		case ITEM_LOGTYPE_WARNING:
			return "Warning";
		case ITEM_LOGTYPE_ERROR:
			return "Error";
		case ITEM_LOGTYPE_FAILURE_AUDIT:
			return "Failure Audit";
		case ITEM_LOGTYPE_SUCCESS_AUDIT:
			return "Success Audit";
		default:
			return "unknown";
	}
}

#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