reserve x for set,
  k for Element of NAT;
reserve s for State of SCMPDS;
reserve d1,d2,d3,d4,d5 for Element of SCM-Data-Loc,
  k1,k2,k3,k4,k5,k6 for Integer;
reserve I for Instruction of SCMPDS;
reserve a,b,c for Int_position;

theorem
  InsCode (AddTo(a,k1,b,k2)) = 9;
