function ff_valid_time(element, message)
{
    var check = /^(1[012]|[1-9]):[0-5][0-9]$/;
    if (!check.test(element.value)){
        if (message=='') message = element.name+" is not a valid time.\n";
        ff_validationFocus(element.name);
        return message;
    } // if
    return '';
} // ff_valid_time