APB Heading vs Bearing

[ironman]

I would reconstruct the APB handling as follows: if Bearing Origin To Destination (8, 9) is provided in the APB sentence plus an XTE (3, 4, 5), the autopilot applies a correction for the XTE, like pypilot does with apb.xte.gain. If you provide Heading To Steer (13, 14), like OpenCPN and the autopilot_route plugin does, the autopilot disregards the other fields but steers this heading-to-steer instead. This way, you can cater for the raymarine consumers who want to try to use the dumb xte based steering, but also the enlightened opencpn users and even more enlightened autopilot_route plugin users. EDIT: This reconstruction is my interpretation of the superfluous fields present in the APB sentence, and my suggestion for how pypilot should handle this superfluousness.