What is right way to use lang and dir attribute in td element ?

Question

Which method should I use?

1. <td><span title="Arabic-language text"><span lang="ar" dir="rtl"></span></span></td>
2. <td lang="ar" dir="rtl"></td>

Above second is my method. Wikipedia use first method. But when I use dir="rtl" in span element then dir="rt" is not working. Why? It's working when I use dir="rt" in td element.