⊦ validref(str, r, ty, st) ↔ r = jvmref ∨ st[r -- _type] .type ≤ ty ∧ ¬ junkref(str, r, st)
⊦ newref(r, st) → junkref(str, r, st)
[[CONCRETESIMPRULES : ()], [EXTRATERMS : (st, ty, r, str)]]