usefor-article-03 February 2000

4.4.2.  Character Sets within Article Bodies

   Within article bodies, the CES and CCS implied by any Content-
   Transfer-Encoding and Content-Type headers [RFC 2045] SHOULD be
   applied by reading agents. In the absence of such headers, reading
   agents cannot be relied upon to display correctly more than the US-
   ASCII characters.
[Observe that reading agents are not forbidden to "guess", or to
interpret as UTF-8 regardless, which would be the simplest course for
them to take.]

        NOTE: It is not expected that reading agents will necessarily be
        able to present characters in all possible character sets,
        although they MUST be able to present all US-ASCII characters.
        For example, a reading agent might be able to present only the
        ISO-8859-1 (Latin 1) characters [ISO 8859], in which case it
        SHOULD present undisplayable characters using some distinctive
        glyph, or by exhibiting a suitable warning. Older reading agents
        that do not understand Mime headers or UTF-8 should be able to
        display bodies in US-ASCII (with some loss of human
        comprehensibility) except possibly when the Content-Transfer-
        Encoding is "8bit".

   Followup agents MUST be careful to apply appropriate encodings to the
   outbound followup. A followup to an article containing non-ASCII
   material is very likely to contain non-ASCII material itself.