Section 7.1 of RFC 1521 makes several assertions about the "text"
Content-Type, in particular, the handling of the charset parameter
(that the default character set, which must be assumed in the absence
of a charset parameter, is US-ASCII), and that the combination CRLF is
used to mean a new line.
I think this means that if we're going to actually register text/html
rather than application/html, we'll have to either be very careful to
supply the charset parameter directly, or else attempt to bend the
rules laid out in RFC 1521.
In general, Internet protocol standards should only talk about how
things are sent out over the net. How you store them locally is up to
you.