Ambiguous "may not"

[pdonahue-ventana]

There are several instances of "may not" in https://github.com/riscv/tg-nexus-trace/blob/master/docs/RISC-V-Trace-Control-Interface.adoc

For instance: "This register may not be implemented if the sink type doesn’t require an address." Does that mean that the register must not be implemented or that it might not be implemented?

I think that the document should entirely avoid "may not" to improve clarity. Even in places that are seemingly clear, use "might not" or "must not" as appropriate.