Definition Cong_tagged A B C D := Cong A B C D.

(* Specifications: *)
Lemma Cong_Cong_tagged : forall A B C D, Cong A B C D -> Cong_tagged A B C D.
Lemma Cong_tagged_Cong : forall A B C D, Cong_tagged A B C D -> Cong A B C D.