https://commonflow.org/https://commonflow.org/spec/1.0.0-rc.1/https://commonflow.org/spec/1.0.0-rc.2/https://commonflow.org/spec/1.0.0-rc.3/https://commonflow.org/spec/1.0.0-rc.4/https://commonflow.org/spec/1.0.0-rc.5/