function IsEmpty(aTextField) {
	return aTextField.value.length == 0 || aTextField.value == null;
}

function IsValidUsername(aTextField) {
	var filter=/^\w+([\.\-]\w+)*$/;
	return filter.test(aTextField.value);
}

function IsValidEmail(aTextField) {
	var filter=/^[^\s@]+@([\w\-]{2,63}\.)+[a-z]{2,6}$/i;
	return filter.test(aTextField.value);
}

function isChecked(aRadioButtonField) {
	for(counter=0; counter < aRadioButtonField.length; counter++) {
		if (aRadioButtonField[counter].checked) return true;
	}
	return false;
}