What language are you looking at? As long as you use romanized characters, you can do non-standard alphabet characters this way.:
é (represents é. Add a semicolon after it to get this. I had to remove it because it got changed to the character)
I don't know exactly how they're doing asiatic characters, as I don't own my copy in an asiatic language (or any other non-roman alphabet), but for everything else, you've just got to use the old school way of doing characters. Back in the dos days, if we wanted to insert a character like that, we'd hold down the alt key then press 0, 2, 3, and 3. This would produce one character, but wouldn't be the easiest, so stuff like this usually was dropped. This type of imput is still around to some degree, and you can get the code for them through character map. Just look for the alt+ area down below in the lower right corner.The number after the alt+ will be the number you want (minus the zero). Hope this helps.
EDIT: Actually, I looked on wiki, and here's a good help if you'd like to keep the formatting the
same. However, if you don't want to do that, you can change it this way:
Change the "ISO-8859-1" in <?xml version="1.0" encoding="ISO-8859-1"?> to one of the following:
"UTF-7" or "UTF-8" or another encoding (UTF should cover almost every language in the world, but if it doesn't cover yours, there's others).