The operator which is used to operate on the schedule table. There are three commands: 1. 'ADD: action, mm/dd/yyyy, hh:mm:ss, week_day, repeat' indicates to add a new entry to the schedule list. 2. 'REPLACE: i, action, mm/dd/yyyy, hh:mm:ss, week_day, repeat' indicates to replace the i-th entry in the table with the new settings. 3. 'DELETE:n1, n2' indicates to delete the entries ranging from number n1 to number n2 from the schedule table. 'action' could be the following: General System Test (1) Quick Battery Test (2) Deep Battery Test (3) Turn On UPS (11) Turn Off UPS (21) Turn On Outlet (100+x) Turn Off Outlet (200+x) where x indicates the outlet number. 'mm/dd/year' and 'hh:mm:ss' specify the action's starting time. 'repeat' indicates the frequency of the action, it could be Once(1), Daily(2), Weekly(3) and Monthly(4). 'week_day' indicating the day of week is meaningful only when the repeat is set to Weekly, and it could be Sun(0), Mon(1), ..., and Sat(6). For example, '1, 07/08/1994, 15:30:00, 0, 4' indicates that the UPS will do a General System Test at 3:30 PM every month from July 8, 1994. '203, 06/20/1995, 07:00:00, 0, 1' indicates that the UPS will turn off outlet #3 at 7 o'clock on June 20, 1995 and do it only once.