Some IPO's aren't on a network, therefore need a way to manage time. As in literally not on a network, no connection to a PC with manager, or anything. No NTP, no RC868 requests from Manager.
So you give a user sytem phone rights (level 1) and they can change the date/time from the menu of a 14xx/16xx. Features/phone user/system admin/time or date... FWIW * = : when setting the time.
GB