function fillVehicle(){ 
 // this function is used to fill the category list on load
addOption(document.form.Vehicle, "Car", "Car", "");
addOption(document.form.Vehicle, "Motorcycle", "Motorcycle", "");
}

function SelectClass(){
// ON selection of category this function will work

removeAllOptions(document.form.Class);
addOption(document.form.Class, "", "Class", "");

if(document.form.Vehicle.value == 'Car'){
addOption(document.form.Class,"A", "A");
addOption(document.form.Class,"B", "B");
addOption(document.form.Class,"B1", "B1");
addOption(document.form.Class,"C", "C");
addOption(document.form.Class,"D", "D");
addOption(document.form.Class,"E", "E");
addOption(document.form.Class,"F", "F");
addOption(document.form.Class,"G", "G");
addOption(document.form.Class,"G1", "G1");
addOption(document.form.Class,"M", "M");


}
if(document.form.Vehicle.value == 'Motorcycle'){
addOption(document.form.Class,"A", "A");
addOption(document.form.Class,"B", "B");
addOption(document.form.Class,"C", "C", "");
}

}
////////////////// 

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);
}