IOType

IOType (from scenerystack/tandem) describes how a class serializes for PhET-iO state (schema, toStateObject / applyState, methods, docs). Built-in Properties already carry NumberIO, StringIO, and similar types.

SceneryStack apps that are not PhET-iO products do not author IOTypes. Prefer keeping state in ordinary Propertys. Background: PhET-iO and Instrumentation. Ready-made types: Built-in IOTypes.