Function pm#from/to_place__from/toplace (process -> spatial_object)
  supertype:  from/to  relation_from_process_only
  subtype:  from_place (process -> spatial_object)
  subtype:  to_place__destination (process -> spatial_object)
  subtype:  via_place__viaplace__via (process -> spatial_object)
  subtype:  path (process -> spatial_object)