satisfies a condition F in the underlying condition system if ⟨P, S, I, O, t⟩ |= F, where ⟨P, S, I, O, t⟩ |= true ⟨P, S, I, O, t⟩ |= WaitFromStart(p, t1, t2) iff ∃n · n ∈ V (S) ∧ n = target(p) ∧ t1 ≤ t − ts (n) ≤ t2 ⟨P, S, I, O, t⟩ |= WaitFromEnd(p, t1, t2) iff ∃n · n ∈ V (S) ∧ n = target(p) ∧ te(n) ̸= ⊥ ∧ t1 ≤ t − te(n) ≤ t2 ⟨P, S, I, O, t⟩ |= EndScenario iff ∀p · p ∈ out(root(P)) ⇒ te(target(p)) ̸= ⊥ ⟨P, S, I, O, t⟩ |= WaitEvent(e) iff e ∈ I ⟨P, S, I, O, t⟩ |= F ∧ G iff ⟨P, S, I, O, t⟩ |= F and ⟨P, S, I, O, t⟩ |= G ⟨P, S, I, O, t⟩ |= F ∨ G iff ⟨P, S, I, O, t⟩ |= F or ⟨P, S, I, O, t⟩ |= G Arias, Desainte-Catherine and Rueda A Tree-Based Operational Semantics for Interactive Multimedia Scores 20/32 20/32