function SelectSubCat(rad){
  // ON selection of category this function will work
  removeAllOptions(document.drop_list.SubCat);

  if(rad.value == 'US'){
    addOption(document.drop_list.SubCat,"10", "California");
    addOption(document.drop_list.SubCat,"41", "Maryland");
    addOption(document.drop_list.SubCat,"43", "Michigan");
    addOption(document.drop_list.SubCat,"45", "Missouri");
    addOption(document.drop_list.SubCat,"51", "New Hampshire");
    addOption(document.drop_list.SubCat,"58", "Oregon");
    addOption(document.drop_list.SubCat,"65", "Texas");
    addOption(document.drop_list.SubCat,"67", "Virginia");
  }
  else if(rad.value == 'CAN'){
    addOption(document.drop_list.SubCat,"15", "British  Columbia");
    addOption(document.drop_list.SubCat,"11", "Nova Scotia");
    addOption(document.drop_list.SubCat,"19", "Ontario");
  }
}
////////////////// 

function removeAllOptions(selectbox)
{
	var i;
	for(i=selectbox.options.length-1;i>=0;i--)
	{
		//selectbox.options.remove(i);
		selectbox.remove(i);
	}
}
function addOption(selectbox, value, text )
{
	var optn = document.createElement("OPTION");
	optn.text = text;
	optn.value = value;
	selectbox.options.add(optn);
}