function reset_form(form) {
	form.units[0].checked = 1
	form.serv_type[0].checked = 1
	form.length.value = ""
	form.width.value = ""
	form.height.value = ""
	form.weight.value = ""
	form.length.focus()
}

function calculate(form) {

	if ((form.units[0].checked == 1) && (form.serv_type[0].checked == 1)) {
		df = 5000
	}
	if ((form.units[0].checked == 1) && (form.serv_type[1].checked == 1)) {
		df = 3000
	}
	if ((form.units[1].checked == 1) && (form.serv_type[0].checked == 1)) {
		df = 305
	}
	if ((form.units[1].checked == 1) && (form.serv_type[1].checked == 1)) {
		df = 183
	}

	form.weight.value = Math.round(100 * eval(form.length.value)
			* eval(form.width.value) * eval(form.height.value) / df) / 100
}