classDiagram class Actor { category contracts : Optional[List[Contract]] id : str parent_actor : str type : Optional[SubTypeEnum] } class ActorTypeEnum { name } class NonFirmActor { nfATO_capacity_kw : float nfATO_endtime : float nfATO_starttime : float } class SubTypeEnum { name } NonFirmActor --|> Actor ActorTypeEnum --* Actor : category