The "Last Maintenance" is the date of the last time the database item appeared on a weekly schedule.
The "Next Maintenance" is the next date it is due to be serviced again.

The "Interval" is the time period, in days, between which the database item will be serviced, calculated by the maintenance service software

"Seasonal" is "T" for true & "F" for false, indicating whether an item has a only a certain period during the year in which it should be serviced. An "F" indicates that an item will be on the schedule during the entire year, and a "T" indicates that it is a seasonal item. An example might be: A snow blower that you only want on the schedule from September 1st - April 30th.

If an item is shown with an "F", it will be on the schedule for the entire year,
beginning from 01/01 (Jan 1) to 12/31 (Dec 31).

If an item is going to be seasonal it will show a "T" and the dates between
which it will be serviced will be indicated here at the Begin Season and the End Season.

These entries are made in the "Edit Database" spreadsheet and are displayed on this screen.