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Re: character sets

1991-05-02 09:09:17

I think most people would agree that intermediate MTAs should not
modify the contents of messages. 

Erik, I think we must have stronger statement:  MTAs _must_ not modify the
contents of the message.  Interpretation of the message contents has to be
on a peer to peer basis.  Otherwise, we end up in the horrible tangle of
being forced to prove that all combinations of intermediate transformations
are reversible.

Further, we're in the unfortunate position that not all enclaves have the
same default interpretation of character sets - witness your own example:

Within our enclave (our company), we have agreed to use the Shift-JIS
encoding, which gets converted automatically at our gateways. So if I
try to send Latin-1, the gateway will think that it is Shift-JIS, and
the message will get messed up. 

I'm impressed that my message will get to you, and you'll be able to read
it, despite the fact that my default encoding is ASCII and yours is
Shift-JIS.  But there's a fundamental problem in this approach.  We want to
define a scheme which enables us to exchange TeX dvi files (for example). 
Any intermediate gateway between my UA and yours permitted to transform the
message text must insure the transformation performed is appropriately
notated so that the corresponding UAs can undo the transforms.  But that
presumes that all UAs are equally capable of performing those
transformations.  This is a _lot_ of extra baggage UAs have to carry around
just so that you and I can exchange a TeX file.  I contend it is _much_
simpler and more reliable to prohibit intermediate transformations by the

(But is this realistic knowing intermediate transformations already exist?)

I think we will eventually have to agree upon a standard multilingual
encoding, in much the same way that we have agreed to use ASCII until

Since you are not using ASCII to read this message, I'm not so sure we've
agreed about that :-)

However, I think there
*is* a great demand to mix the main European languages. So we should
at least provide these users with something. I think the
Quoted-Readable encoding would be perfect for this, since users with
old UAs should be able to read this, and new UAs will be able to
convert it. So let's concentrate on the Quoted-Readable encoding, and
let's make it EBCDIC-safe i.e. unaffected by ASCII<->EBCDIC

Unfortunately, this would require a transformation which is neither ASCII
nor EBCDIC, and liable to satisfy no one.

This subject is still somewhat
confusing for me, so I may have made some mistakes in the reasoning
above. I would be grateful if someone could point out the mistakes.

I don't know about mistakes, but we certainly have differing opinions...:-)



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