| ⊦ validref(str, r, ty, st) ∧ is_fskey(sk) ∧ (is_referencevalue(val) → validref(str, val .refval, sk .fs .type, st) ∧ is_reftype(sk .fs .type)) ∧ (¬ is_referencevalue(val) → is_fskey(sk) ∧ okval(val, sk .fs .type) ∧ sk .fs .type ≠ void_type ∧ sk ≠ _length) → validref(str, r, ty, st[r0 -- sk, val]) |