Once I'd fixed that, I've made some substantial progress. The Waypoints facility is now working and enables me to store and update waypoints. I've also implemented the Folios facilities, so that I can test the ability to refer to a Folio from a Waypoint. The usual (for Microsoft Access) faciliy to define a new Folio from the Waypoint screen is now also working.
With those two facilities up and running, the next stage is to parameterise as much as possible so that the process of adding a new facility is as painless as it is with the Microsoft Access version. That's tomorrow's task.