flowchart LR
  S1((NestedWithOptionalShape))
  S1-.->|"http:‎//example.org/subject"|S1_0[ ]
  S1_0((OptionalNestedNodeShape))
  S1_0-->|"http:‎//www‎.w3.org/2000/01/rdf-schema#label"|S1_0_1[ ]