public abstract string[] writeable_properties { get; }

The names of the properties of this Persona which are writeable.

If a property name is in this list, setting the property should result in the updated value being stored in the backend's permanent storage (unless it gets rejected due to being invalid, or a different error occurs).

It's intended that this property value will be constant for a given Persona subclass, but this isn't guaranteed; it's possible that Persona subclasses may vary the value of this property at run time.