usefor-article-08 August 2002

5.5.2.  Encoded newsgroup-names

   Where it is required to transport an article across some medium that
   cannot reliably convey the full 8 bits of each octet, such as when
   gatewaying it into Email (8.8.1), or when emailing it to a moderator
   or constructing the submission address of the moderator (8.2.2), it
   may be necessary to encode any newsgroup-name within a Newsgroups- or
   Followup-To-header that contains any non-ASCII character. For that
   purpose, the following algorithm is provided:

   1. Initially, the newsgroup-name is in the form of a sequence of
      octets representing that name in the UTF-8 character set.

   2. Each octet in the name in the range 0x80-FF is replaced by an "="
      character (US-ASCII 61), followed by two characters representing
      that octet in hexadecimal, in which the hexadecimal digits "A"
      through "F" MUST be in uppercase.

   3. Each octet in the name in the range 0x00-7F remains unaltered (and
      thus MUST NOT be replaced by its hexadecimal equivalent).

        NOTE: Observe that this algorithm provides a unique encoding for
        each newsgroup-name. Observe also that within the unaltered
        range 0x00-7F, only the octets 0x2B, 0x2D-2E, 0x30-39, 0x41-5A,
        0x5F, and 0x61-7A can appear in a newsgroup-name.

   This standard provides no authority for the use of this algorithm
   other than in the context of newsgroup-names occurring within headers
   being conveyed by email. In particular, it MUST NOT be used within
   any article conveyed by the Netnews protocols and thus, if an email
   using it is subsequently returned to the Netnews environment, it MUST
   be decoded back into UTF-8.

        NOTE: Although the encoding defined by [RFC 2047] is available
        for use with other headers containing non-ASCII characters, the
        Newsgroups-header, being a structured header, is not one of the
        contexts permitted for its use (and moreover it would not
        produce a unique encoding nor cope well with newsgroup-names of
        excessive length). Therefore it SHOULD NOT be used within the
        Newsgroups-header.