(* <Warning> : Syntax is discontinued *)
Notation Kas := (KeyX Aid) (only parsing).
(* <Warning> : Syntax is discontinued *)
Notation Kbs := (KeyX Bid) (only parsing).
(* <Warning> : Syntax is discontinued *)

Axiom disjKasKeyAB : forall d1 d2 : D, KeyAB d1 d2 <> KeyX Aid.
Axiom
rngDDKKeyAB1 : forall d1 d2 : D, In (B2C (K2B (KeyAB d1 d2))) rngDDKKeyAB.