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[1] (draft-ietf-822ext-qreadable-02.txt から)

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[PRE[
Network Working Group                                      Keld Simonsen
INTERNET-DRAFT                                   Danish Unix Users Group
                                              Philippe-Andre Prindeville
                                                           Telecom Paris
                                                         4th August 1991

Mnemonic Text Format
]PRE]

*3.  Message Format

As in [2], the message exists as a series of parts, each part being a
group of lines containing characters in the character set employed.

1991年6月の [[MIME]] 原案では、メッセージは一連の部分として
存在し、各部は使われる文字集合中の文字からなる行の集団であります。

Each part may or may not be encoded using this format; we concern 
ourselves in this document solely with those that are.  Within the relevant
parts of the message, ordinary text may have occurrences of the 
following sequence: an intro character, followed by a string of characters
that represent a character mnemonic, as described below.  Similarly, the
intro character may doubled, indicating a single occurence of the
respective symbol in decoded format.

This message format uses the headers "Content-Type:" and 
"Content-Charset:" from [2] and is signified with the new header 
"Mnemonic-Intro:" and the two optional headers "Orig-Content-Charset" and 
"Orig-Mnemonic-Intro:". Case is ignored in these headers.  A description of
these headers and their fields follows.

このメッセージ書式は MIME 原案から「Content-Type:」と
「Content-Charset:」の各頭を、それから2つの任意頭
「Orig-Content-Charset」と「Orig-Mnemonic-Intro:」各頭を使います。
各頭・領域の説明は次の通りです。

**3.1.  Content-Type: Text

If the Content-Type header is present, it must have the first header
field as "Text" according to this specification. The Content-Type header
can also be omitted, as Text is the default content type.  The mnemonic
message format is intended to be read by the end user possibly without
further intervention.

**3.2.  Content-Charset: charset

;; 編註: 長いので適当に段落区切ってます。

The charset is given as one of the coded character set names in [3] and
is the encoding used for the transport.  For general use on the 
Internet, only "ASCII" and "ICS" are allowed.

charset は将来 RFC 1345 になる原案の中の符号化文字集合名の一つで、
転送に使われる符号化方法です。 Internet では通常の使用では、
「ASCII」と「ICS」だけが認められています。

ASCII is the recommended character set, while ICS will be very robust 
for traversing gateways, but it
will cause trouble for (amongst other things) source code for several
programming languages.

ASCII は推奨文字集合です。 ICS は関門を旅するのにとても
力強いでしょうが、プログラム言語のソース・コードなんかで
問題を起こすでしょう。

The use of other character sets are delimited to
agreement between the communicating parties. When such an agreement has
been achieved, or when a User Agent is operating in another character
set than this transport character set, conversion of the message body
part is done according to the tables in [3], as characters occuring in
both encodings are just transformed, and characters not existing in the
receiving coded character set are represented by the intro character of
the receiving coded character set plus the mnemonic from [3], as
described under the intro character.

他の文字集合の使用は通信団体間の合意によります。かような
合意のなされている時、あるいは利用者代理者が転送文字集合から他の文字集合
に変換しようとする時には、メッセージ本体部分の変換は
将来 RFC 1345 になる原案の表に沿い、両符号化方法で使える文字は
普通に変換し、受信側文字集合で存在しない文字は受信側符号化文字集合の
先導文字と将来 RFC 1345 になる原案の記法で表現します。

The characters forming the
mnemonic are translated into the receiving code, which must have these
characters present.  An undefined character in the originating coded
character set is transformed into a question mark character.  The
Content-Type:-header is changed accordingly to reflect such conversion.
Conversion is not allowed if the content-type is not "Text" (which is
the default if the Content-Type header is missing).

記法の文字形は受信符号に変換されますが、必ずそれらの文字表現を
持たなければなりません。元の符号化文字集合の未定義文字は
疑問符文字に変換されます。 Content-Type:(内容型) 頭は
変換を反映して修正されます。 content-type が「Text」(文字列)
(Content-Type 頭が無い時の既定値) でない時は
変換は認められません。

;; 編註: なんとここまで一段落。

An example of changing headers is the following: The UA runs in an 8-bit
character set:

Content-Type: Text
      Content-Charset: ISO_8859-1
      Mnemonic-Intro: 29
      Orig-Content-Charset: ISO_8859-1
      Orig-Mnemonic-Intro: 29

The MTA converts it before sending it to the recepient:

Content-Type: Text
      Content-Charset: ASCII
      Mnemonic-Intro: 38
      Orig-Content-Charset: ISO_8859-1
      Orig-Mnemonic-Intro: 29

**3.3.  Mnemonic-Intro: Intro

The intro character is given as the decimal value of the intro character
in the transport character set. The recommended value is 38 for the
ampersand (&) character in ASCII. Another common value is 29 for the
control character Group Seperator, which may be convenient when operat-
ing in some environments, and ordinary text is not changed.  The intro
character is used for introducing character mnemonics from [3] when a
character is not present in the mail transport character set (as defined
by "charset").  Character mnemonics longer than two characters are sur-
rounded by the underline character. The intro character is doubled to
repesent one occurance of itself.  Characters in the mail transport
character set are normally just represented with their encoding, but may
also be represented by the intro character and the mnemonic encoding.
If the intro character is specified as 0 (zero), it is omitted in the
transport, giving a better readably content, but eliminating the possi-
bility of reversability and introducing an information loss.

**3.4.  Orig-Content-Charset: orig-charset

The orig-charset is given as the original character set name.  This may
be set by the sending User Agent before converting the message into a
character set suitable for transport.  If no orig-charset is specified,
the charset character set is used.

3.5.  Orig-Mnemonic-Intro: orig-intro

The orig-intro character is given as the original intro character as
used by the originating User Agent. The orig-charset and orig-intro may
be used to recreate the message in its original encoding.  If no orig-
intro character is specified, the intro character is used.  If the
orig-intro character is specified as 0 (zero), no intro character was
used in the original content.  On the other hand, having  a non-zero
orig-intro value allows the user to generate characters, that are not
available in the orig-charset.

* License

[[RFCのライセンス]]。

*See also
-<urn:ietf:id:draft-ietf-822ext-qreadable-02>
-[[RFC1345]]
-[[MIME]]
--[[charset]]
-[[RFC822と仲間達の頭領域名]]
--[[Content-Type:領域]]
--[[Encoding:領域]]

* メモ

[4] この [[I-D]] は [[RFC]] にはなりませんでした。

[5] 
今は [[IETF]] のデータベースに残っていませんし、 [[Google検索]]しても全文はどこにも見つかりません。
[TIME[2024-11-11T05:30:13.800Z]]

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