Re: [sheflug] Changine editors?

["Stephen J. Turnbull" <nospam [at] sk.tsukuba.ac.jp>]

>>>>> "damian" == damian bamforth <damian.b [at] Btinternet.com> writes:

    damian> what does MIME stand for,

>From RFC 2045: Multipurpose Internet Mail Extensions

    damian> and what is MIME encryption/decryption?

There is no such thing (to the extent that "crypt" implies a _secret_
code).

MIME en/decoding is a set of protocols that allow any kind of data you
may desire to be sent through internet mail.  Originally, the armoring
function was foremost, as many gateways did evil things like stripping
out (or adding) high bits or escape characters.  Today this is not so
important, most internet mailers can handle binary data.

The second function was identification of the _type_ of the data, to
allow MIME-capable agents to render the data in a nice way.  You might
think of MIME as sort of the HTML equivalent for mail.

However, the MIME identification protocols are more general than HTML.
They are, for example, used in HTTP itself, as a lower layer for
transmissions over the WWW.  They also allow for "content
negotitiation".  Eg, I never see any HTML mail, I tell my MUA to flush
it.  But most MUAs will send both plaintext and HTML format, using a
MIME multipart/alternative protocol.  In that case, I do see the
plaintext, and only that.

So a typical simple mail header will contain lines like the following:

MIME-Version: 1.0
Content-Type: text/plain; charset="ISO-8859-15"

The first line just says "This is MIME."  _Nothing_ else is permitted
except for whitespace and RFC-2822 comments (enclosed in parens).  And
there only ever has been _one_ version, 1.0.  If your MTA sees
something else (several Sun MUAs and DEC MTAs add crap or change the
version), it knows the senders were implemented by illiterate slobs
who Just Don't Get It -- so expect the worst.

The second one says, "this is plain text, display it as is, don't flow
it, don't blink it, etc, etc."  But "it uses the ISO-8859-15 character
set, so interpret the appropriate codes as the Euro currency symbol as
well as various accented characters from languages like French and
German."

Note that in Latin-1, some other character is in the place of the
Euro.  So the MIME header really does identify the "type" of the data,
ie, how to use the bytes you get.

Don't ask me for a simple tutorial, I started with the RFCs.  :-)
ftp://ftp.jaist.ac.jp/Internet/RFC/rfc-index.txt

I don't recommend doing an ls on that directory....

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