The work that should happen on a schedule, scheduled — so it happens before it becomes a work order.
Filters, elevators, roofs, fire systems — whatever needs doing on an interval, against the property or unit it belongs to.
A due schedule creates the work order, assigned and ready, rather than a reminder somebody has to act on.
Monthly, quarterly, annually, or a custom cadence.
What was done, when, and by whom, which is the record you need when a warranty or a claim depends on it.
Assign a schedule to a vendor or to your own maintenance staff.