Waypoint – a record type, which knows at least the date and mileage.
Thus, other types of records, also containing the date and mileage, serve as a waypoint.
Originally created to preserve the history of a trip and mark waypoints of the route – for example, long range can be divided into several sections for further analysis (pace / average speed, etc.).
Another practical aspect of using waypoints – the program updates the forecast for the remainder of fuel in the tank for the last known dressing and mileage. And the introduction of waypoint significantly improves the prognosis.
Especially in uneven odometer situtions – after vacation or business trip, when the car stood long in the parking lot, entering the PT with the current mileage rate will result in a zero balance of fuel.