usefor-article-03 February 2000

6.17.2.  Content-Transfer-Encoding

   Posting agents SHOULD specify "Content-Transfer-Encoding: 8bit" for
   all articles not written in pure US-ASCII and not requiring full
   binary. They MAY use "8bit" encoding even when "7bit" encoding would
   have sufficed. They SHOULD specify "base64" when the content type
   implies binary (i.e. content intended for machine, rather than human,
   consumption).

        NOTE: If a future extension to the MIME standards were to
        provide a more compact encoding of binary suited to transport
        over an 8bit channel, it could be considered as an alternative
        to base64 once it had gained widespread acceptance.

   Posting agents SHOULD NOT specify encoding "quoted-printable", but
   reading agents MUST interpret that encoding correctly.  Encoding
   "binary" MUST NOT be used (except in cooperating subnets with
   alternative transport arrangements) because this standard does not
   mandate a transport mechanism that could support it.

   Injecting and relaying agents MUST NOT change the encoding of
   articles passed to them. Gateways SHOULD ONLY change the encoding if
   absolutely necessary.