| ⌊err0⌋ ∨ err0 = ESUCCESS ⊦ ⟪err := err0; if err = ESUCCESS then avols := ∅ else avols := ?⟫ (err = ESUCCESS → ebm-cons(avols)) |
err = err0, ⌊err0⌋ ∨ err0 = ESUCCESS ⊦ ⟪if err = ESUCCESS then avols := ∅ else avols := ?⟫ (err = ESUCCESS → ebm-cons(avols))