Yes/no/unspecified is a good match for something like `Option<bool>` or `bool?`. Their usage covers every case and nothing needs to be elucidated. With that sa

Yes/no/unspecified is a good match for something like `Option<bool>` or `bool?`. Their usage covers every case and nothing needs to be elucidated. With that said, in a language that supports null and has no compile-time mechanism to detect potential null dereferencing (like modern C# for instance) I might use an enum.