The language in question is Hebrew. One feature that may be of importance to us is the ability to prevent certain characters from appearing anywhere else but at the end of the label (i.e. it can only be the last char of a label), and we have another issue, which I'm not certain is in the scope of this list, any label in Hebrew needs to be written RTL, and if i'm not mistaken, this technically prevents the mixing of Hebrew and non-Hebrew chars in the same label.
--Paul Hoffman, Director --Internet Mail Consortium