Section ZModulo.
Variable digits : positive.
Hypothesis digits_ne_1 : digits <> 1%positive.
Definition wB := base digits.
Definition t := Z.
Definition zdigits := Zpos digits.
Definition to_Z x := x mod wB.
Notation "[| x |]" := (to_Z x)  (at level 0, x at level 99).
Notation "[+| c |]" :=
(interp_carry 1 wB to_Z c)  (at level 0, c at level 99).
Notation "[-| c |]" :=
(interp_carry (-1) wB to_Z c)  (at level 0, c at level 99).
Notation "[|| x ||]" :=
(zn2z_to_Z wB to_Z x)  (at level 0, x at level 99).

Lemma spec_more_than_1_digit: 1 < Zpos digits.