Ltac id_compare x y :=
  destruct (CompSpec2Type (Ident.compare_spec x y)).Ltac id_comp x y H1 H2 H3 :=
  destruct (CompSpec2Type (Ident.compare_spec x y)) as [H1|H2|H3].

(* Specifications: *)
Lemma id2pos_inj x y : id2pos x = id2pos y -> x=y.
Lemma Ilt_irrefl : forall {x}, ~ Ident.lt x x.
Lemma Ilt_trans : forall {x y z}, Ident.lt x y -> Ident.lt y z -> Ident.lt x z.