function chdop (val) {
  var platdop = new Array();
  platdop[1] = new Array();
  platdop[1][1] = 1;
  platdop[1][2] = 1;
  platdop[2] = new Array();
  platdop[2][1] = 1;
  platdop[2][2] = 1;
  platdop[2][3] = 1;
  platdop[3] = new Array();
  platdop[3][3] = 1;
	tmp = platdop[val];
	for (i = 1; i <= 3; i++) {
		if (document.getElementById("delivery"+i)) {
			if (tmp [i]) {
				document.getElementById("delivery"+i).disabled = "";
			} else {
				document.getElementById("delivery"+i).disabled = "disabled";
				document.getElementById("delivery"+i).checked = "";
			}
		}
	}
	if (val == 3) {
    document.getElementById("delivery3").checked = "checked"
  } else {
    document.getElementById("delivery3").checked = ""
  }
}