Infix "%c%" := cmodz (at level 40) : int_scope.

(* Specifications: *)
Lemma cdivz0 x : (x %c/ 0)%Z = 0.
Lemma cdiv0z y : (0 %c/ y)%Z = 0.
Lemma cdivz1 x : (x %c/ 1)%Z = x.