Version 3.0.1 is available upstream. Please consider updating! It seems that version 3.0.1 is available upstream, while the latest version in the Gentoo tree is 2.16.0-r1. You think this warning is false? Read more about it here.
ATD stands for Adaptable Type Definitions. It is a syntax for defining
cross-language data types. It is used as input to generate efficient and
type-safe serializers, deserializers and validators.