Provenance

Where this knowledge came from, and why you can use it under any licence.

The short version

Facts about a protocol are not copyrightable. An implementation of a protocol is. These notes are facts, gathered from packet captures against a real radio and from two MIT-licensed implementations. Nothing here is derived from wfview's GPLv3 source, so building on these notes does not put your project under the GPL.

The longer version

Three sources informed this work.

Packet captures. The primary source. Wireshark against an IC-7300 MK2 on a local network, with a client connecting, negotiating streams, running for a while, and disconnecting. Where a field's meaning was worked out by changing one thing and watching what moved, the notes say so.

kappanhang and rigplane, both MIT. Read as implementations, and the source of several structures here, including the credential obfuscation table, which is reproduced from kappanhang with its copyright notice intact. MIT permits this in any project, commercial or not, provided attribution travels with it.

wfview, GPLv3. Read as documentation of how the radio behaves, in the same way you would read a datasheet. No code, comments, structures or rig definitions were copied from it, and where wfview and kappanhang disagree about a field the notes follow kappanhang and explain the difference.

Why the distinction was worth the effort

It would have been easier to read one mature implementation and transliterate it. That would have produced a derivative work of a GPLv3 project, which is fine if your project is GPLv3 and a serious problem if it is not, and it is a decision that is very expensive to reverse once a codebase is built on it.

Keeping to MIT sources and to independent observation kept the option open, and cost perhaps a few days of extra care. Anyone planning to build on these notes gets that option for free.

If you are building on this

You inherit no obligation from these notes beyond CC BY 4.0 attribution. If you also copy code from kappanhang or rigplane, their MIT notices must ship with your binary, which is a short file rather than a licence change.

If you copy from wfview, your project becomes GPLv3. That is a perfectly good choice, made deliberately. It should not be made by accident.