MessagePack has extension types: https://github.com/msgpack/msgpack/blob/master/spec.md#formats-ext https://github.com/msgpack/msgpack/blob/master/spec.md#form

MessagePack has extension types: https://github.com/msgpack/msgpack/blob/master/spec.md#formats-ext https://github.com/msgpack/msgpack/blob/master/spec.md#forma... I experimented using them to implement a limited atom/token spec for use on Arduino.