Is base64 also unicode? is there another name for it?
Base64 has nothing to do with unicode. You can encode unicode text using base64, just as you can encode anything else using base64.
Base64 is a MIME encoding, used to encode arbitrary bytes into a format that can safely be transmitted by mail. There's base64 (usually used for binary attachments, but also for e.g. chinese text), there's andother called quoted-printable (usually used for text in languages other than English, e.g. my native Norwegian) and then there's the no-op encodings such as 7bit (usually used for English text).
That's just a rough description - any mail sender can choose freely between all three encodings. All mail readers effectively have to decode all three.
If you're writing a program to deal with mail, I suggest that you get a book about this. http://www.powells.com/cgi-bin/biblio?inkey=2-1565924797-5 looks like a decent introduction.
--Arnt
