Convert Unicode domain names to and from the ASCII Punycode used by IDNA.
Punycode
is the encoding defined in RFC 3492 that represents Unicode text using only the
ASCII characters allowed in host names. It is the basis of
internationalized domain names
(IDNA). When you encode a domain, each label that contains non-ASCII characters
is converted and given an "xn--" prefix, while plain ASCII labels pass through
unchanged. Enter one domain or string per line.