function seleccion(val){
	var valor;
	valor=val.value;
	if(valor==1){
		document.getElementById('area').innerHTML="RBD";
		digito = document.getElementById('digiv');
		digito.style.display = 'none';
		document.forms[0].id_user.style.width = '120px';
	}
	else{
		document.getElementById('area').innerHTML="RUT";
		digito = document.getElementById('digiv');
		digito.style.display = 'inline';
		document.forms[0].id_user.style.width = '89px';
	}
	
	//document.getElementById('area').innerHTML=val.value
}


function isNumberKey(evt){
	var charCode = (evt.which) ? evt.which : evt.keyCode
	
	if (charCode > 31 && (charCode < 48 || charCode > 57))
		return false;
	
	return true;
}

function eliminar_opciones(combo){
	largo_cbo = combo.length;
	for (i=largo_cbo;i>=0;i--){
		combo.options[i]=null;
	}
}