Definition Zdigits2 n :=
match n with
| Z0 => n
| Zpos p => Zpos (digits2_pos p)
| Zneg p => Zpos (digits2_pos p)
end.

(* Specifications: *)
Lemma Zdigits2_Zdigits :
forall n, Zdigits2 n = Zdigits radix2 n.