2.2. URL Character Encoding Issues

   URLs are sequences of characters, i.e., letters, digits, and special
   characters. A URLs may be represented in a variety of ways: e.g., ink
   on paper, or a sequence of octets in a coded character set. The
   interpretation of a URL depends only on the identity of the
   characters used.

   In most URL schemes, the sequences of characters in different parts
   of a URL are used to represent sequences of octets used in Internet
   protocols. For example, in the ftp scheme, the host name, directory
   name and file names are such sequences of octets, represented by
   parts of the URL.  Within those parts, an octet may be represented by
   the chararacter which has that octet as its code within the US-ASCII
   [20] coded character set.