Standard for adding Dio fields

[AlexV525]

We should have standards for adding fields to Dio regarding static constants, private/public fields, getter/setter, and methods, including:

• How should we name them? Prefixes, cases, length?
• Whether they should be private fields + public getters? Or simply non-final fields for the public?
• Something else...

[kuhnroyal]

This raises the question of mutability of dio instances in general. Right now everything is pretty much mutable, so new fields should be as well.
But I hate that :)