The reason for 76 characters limit of a MIME encoded header line?

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Article #143

#143

From: Masanori HATA
Date: Wed, 16 Nov 2005 05:58

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Hello to all,

I have a question about the number of characters that each of
multiple-line header field that contains one or more 'encoded-words' is
limited to 76 in RFC 2047 (section 2) (or in its former version 1522).

Why is it 76 characters? Why isn't it 78 characters?

In RFC 2822 (section 2.1.1) it is said that the number of characters in
a line SHOULD be no more than 78 characters, excluding the CRLF.

So the CRLF is excluded that each line of characters can be upto 80
characters including the trailing CRLF.

What is the reason for the decreasing two characters of the number of
characters in a MIME encoded header line?

Could anyone please give me suggestion? Any comment is appreciated.

Regards,

-- 
Masanori HATA

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From: Masanori HATA <hata@iname.com>
Newsgroups: comp.mail.mime,fj.mail
Subject: The reason for 76 characters limit of a MIME encoded header line?
Date: Wed, 16 Nov 2005 14:58:35 +0900
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