I'm trying to work on a fix for #7, which should only be a one or two line change to the parent mbed-os, however I can't figure out which version/branch/tag/fork of mbed-os was used to build the current release of ArduinoCore-nRF528x-mbedos.

The git commit logs seem to be referencing mbed-os-5.4.0-rc2, but that doesn't make any sense, since that release is over two years old and the ARDUINO_NANO33BLE target only appeared in 5.13.4. I think this is either a mistake, or somebody is working off of a weird fork that I can't find.

Right now there's just mbed-to-arduino script, but this appears to be both partially incomplete as well as subtly incompatible with most of the mbed-os releases that I've tried to work with (from @ARMmbed and @facchinm). Playing with the dummy mbed project and figuring out how to generate the correct artifacts for the arduino core should be relatively straightforward... I just need to know which mbed-os to use.

It would be nice if there were a formal way to identify the mbed-os release. This could be as simple as a changelog with a git repo url + commit id. Or maybe a submodule?