PROC FillRed() IS 
  PS.SetRGB(1, 0, 0); PS.Fill() 
END;

PROC Cmd0() IS 
  IF 
    VAR 
      a = (116, 440), 
      b ~ (42, 333), 
      c ~ (190, 333), 
      d ~ (42, 226), 
      e ~ (190, 226), 
      f ~ (190, 440), 
      g ~ (116, 333), 
      h ~ (116, 226) 
    IN 
      b VER d AND 
      c VER e AND 
      b HOR c AND 
      d HOR e AND 
      (a, b) CONG (a, c) AND 
      f = Geometry.HV(a, c) AND 
      (f, c) CONG (c, e) AND 
      g = Geometry.Mid(b, c) AND 
      h = Geometry.Mid(d, e) -> 
        PS.SetWidth(3); 
        DiGraph.SetRadius(25); 
        DiGraph.Node(a); 
        DiGraph.Node(b); 
        DiGraph.Node(c); 
        DiGraph.Straight(a, b); 
        DiGraph.Straight(a, c); 
        DiGraph.Node(d); 
        DiGraph.Node(e); 
        DiGraph.Straight(b, d); 
        DiGraph.Straight(c, e); 
        PS.SetFont("Times-Bold", 
                   24); 
        DiGraph.Label(a, "A"); 
        DiGraph.Label(b, "B"); 
        DiGraph.Label(c, "C"); 
        DiGraph.Label(d, "D"); 
        DiGraph.Label(e, "E"); 
        DiGraph.Curved(a, g, h, e) 
    END 
  FI 
END;