reserve A,A1,A2,B,C,D for Ordinal,
  X,Y for set,
  x,y,a,b,c for object,
  L,L1,L2,L3 for Sequence,
  f for Function;
reserve fi,psi for Ordinal-Sequence;
reserve e,u for set;

theorem
  rng psi c= sup psi
proof
  let e be object;
  assume
A1: e in rng psi;
  then e is Ordinal by Th48;
  hence thesis by A1,Th19;
end;
