In general, the analogue to reference types in ProtoFlux is the object type. This can cause some confusion when using nodes that interact with FrooxEngine (such as a Data Model Store) vs nodes that are contained entirely within protoflux (such as a Local). A slot is an Object Ref in the Data Model, but an Object alone in ProtoFlux contexts. A string is a value in the Data Model, but an Object Field in ProtoFlux contexts.