Here's where I'll explain how to describe flight plans using the UDB's variant of the LOGO programming language.
For now, the best documentation is the flightplan-logo.h file iteslf (code.google.com).
Also check out the UDB Logo Editor. It is located at:
Tools/UDB_Logo_Editor/udb_logo_editor.html
in the download.
This tool lets you run UDB Logo programs on a Google Maps page, to preview the flight plan. It's great for learning and debugging. I suggest testing all UDB Logo programs in this tool before flying them.
Note that there are a few UI elements in this tool that need some explanation:
Wiki: CompatibleSoftware
Wiki: FlightPlans
Wiki: Sidebar
Wiki: SidebarMP33