Is there a "Flow Diagram" for ATC, that could be included in the SDK

ATC seems to have a mind of its own, and often seems to handle the same flight
plan, in very different ways: some it seems to get hopelessly lost in. It
would be helpful if there was a maintained Flow Diagram, depicting what ATC is
meant to be coded to do. I cannot imagine that reviewing the code without such
a documentation , lends itself to a stable process. If such documentation does
not exist to base the current ATC on, this may explain why ATC appears to be
so unstable.