This format can...
read and write waypoints
This format is derived from the xcsv format, so it has all of the same options as that format.
This is the format used by the FlySight GPS for wingsuit pilots.
Interfacing with the FlySight is pretty simple. FlySight acts like a USB disk when connected to a computer. Files are organized into folders by date, and individual files within the folder are named according to the time the log started (UTC). The files themselves are CSV text supported by this format.