function OpenReadyToReturnWindow(url, orderStatus) {
    if (orderStatus == 'ISD') {
        ShowWindow(url + levelQstr, 530, 380, nextLevelID);
        return false;
    } else if (orderStatus == 'RTR') {
        alert("Sorry, this books is already marked as ready to return.");
        return false;
    }
    else if (orderStatus == 'RET') {
        alert("Sorry, you can not marked book as Ready To Return as it is alreayd Returned.");
        return false;
    }
    else {
        alert("Sorry, you can not marked book as Ready To Return as it is not Issued.");
        return false;
    }
}