1sink: "{ S[] -> a[] }" 2must_source: "{ T[] -> a[] }" 3may_source: "{ U[] -> a[] }" 4schedule: 5 domain: "{ U[]; S[]; T[] }" 6 child: 7 sequence: 8 - filter: "{ T[]; U[] }" 9 - filter: "{ S[] }" 10