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wakaba |
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*3. Message Format (draft-ietf-822ext-qreadable-02.txt から)
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As in [2], the message exists as a series of parts, each part being a
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group of lines containing characters in the character set employed.
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1991年6月の [[MIME]] 原案では、メッセージは一連の部分として
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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。
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Each part may or may not be encoded using this format; we concern
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ourselves in this document solely with those that are. Within the relevant
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parts of the message, ordinary text may have occurrences of the
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following sequence: an intro character, followed by a string of characters
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that represent a character mnemonic, as described below. Similarly, the
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intro character may doubled, indicating a single occurence of the
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respective symbol in decoded format.
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This message format uses the headers "Content-Type:" and
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"Content-Charset:" from [2] and is signified with the new header
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"Mnemonic-Intro:" and the two optional headers "Orig-Content-Charset" and
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"Orig-Mnemonic-Intro:". Case is ignored in these headers. A description of
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these headers and their fields follows.
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このメッセージ書式は MIME 原案から「Content-Type:」と
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「Content-Charset:」の各頭を、それから2つの任意頭
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「Orig-Content-Charset」と「Orig-Mnemonic-Intro:」各頭を使います。
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各頭・領域の説明は次の通りです。
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**3.1. Content-Type: Text
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If the Content-Type header is present, it must have the first header
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field as "Text" according to this specification. The Content-Type header
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can also be omitted, as Text is the default content type. The mnemonic
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message format is intended to be read by the end user possibly without
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further intervention.
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**3.2. Content-Charset: charset
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;; 編註: 長いので適当に段落区切ってます。
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The charset is given as one of the coded character set names in [3] and
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is the encoding used for the transport. For general use on the
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Internet, only "ASCII" and "ICS" are allowed.
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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、
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転送に使われる符号化方法です。 Internet では通常の使用では、
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「ASCII」と「ICS」だけが認められています。
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ASCII is the recommended character set, while ICS will be very robust
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for traversing gateways, but it
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will cause trouble for (amongst other things) source code for several
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programming languages.
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ASCII は推奨文字集合です。 ICS は関門を旅するのにとても
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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
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問題を起こすでしょう。
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The use of other character sets are delimited to
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agreement between the communicating parties. When such an agreement has
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been achieved, or when a User Agent is operating in another character
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set than this transport character set, conversion of the message body
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part is done according to the tables in [3], as characters occuring in
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both encodings are just transformed, and characters not existing in the
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receiving coded character set are represented by the intro character of
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the receiving coded character set plus the mnemonic from [3], as
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described under the intro character.
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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
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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
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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
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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
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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
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先導文字と将来 RFC 1345 になる原案の記法で表現します。
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The characters forming the
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mnemonic are translated into the receiving code, which must have these
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characters present. An undefined character in the originating coded
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character set is transformed into a question mark character. The
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Content-Type:-header is changed accordingly to reflect such conversion.
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Conversion is not allowed if the content-type is not "Text" (which is
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the default if the Content-Type header is missing).
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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
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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
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疑問符文字に変換されます。 Content-Type:(内容型) 頭は
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変換を反映して修正されます。 content-type が「Text」(文字列)
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(Content-Type 頭が無い時の既定値) でない時は
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変換は認められません。
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;; 編註: なんとここまで一段落。
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An example of changing headers is the following: The UA runs in an 8-bit
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character set:
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Content-Type: Text
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Content-Charset: ISO_8859-1
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Mnemonic-Intro: 29
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Orig-Content-Charset: ISO_8859-1
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Orig-Mnemonic-Intro: 29
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The MTA converts it before sending it to the recepient:
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Content-Type: Text
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Content-Charset: ASCII
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Mnemonic-Intro: 38
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Orig-Content-Charset: ISO_8859-1
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Orig-Mnemonic-Intro: 29
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**3.3. Mnemonic-Intro: Intro
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The intro character is given as the decimal value of the intro character
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in the transport character set. The recommended value is 38 for the
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ampersand (&) character in ASCII. Another common value is 29 for the
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control character Group Seperator, which may be convenient when operat-
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ing in some environments, and ordinary text is not changed. The intro
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character is used for introducing character mnemonics from [3] when a
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character is not present in the mail transport character set (as defined
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by "charset"). Character mnemonics longer than two characters are sur-
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rounded by the underline character. The intro character is doubled to
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repesent one occurance of itself. Characters in the mail transport
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character set are normally just represented with their encoding, but may
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also be represented by the intro character and the mnemonic encoding.
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If the intro character is specified as 0 (zero), it is omitted in the
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transport, giving a better readably content, but eliminating the possi-
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bility of reversability and introducing an information loss.
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**3.4. Orig-Content-Charset: orig-charset
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The orig-charset is given as the original character set name. This may
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be set by the sending User Agent before converting the message into a
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character set suitable for transport. If no orig-charset is specified,
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the charset character set is used.
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3.5. Orig-Mnemonic-Intro: orig-intro
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The orig-intro character is given as the original intro character as
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used by the originating User Agent. The orig-charset and orig-intro may
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be used to recreate the message in its original encoding. If no orig-
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intro character is specified, the intro character is used. If the
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orig-intro character is specified as 0 (zero), no intro character was
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used in the original content. On the other hand, having a non-zero
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orig-intro value allows the user to generate characters, that are not
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available in the orig-charset.
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*See also
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-<urn:ietf:id:draft-ietf-822ext-qreadable-02>
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-[[RFC1345]]
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-[[MIME]]
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--[[charset]]
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-[[RFC822と仲間達の頭領域名]]
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--[[Content-Type:領域]]
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--[[Encoding:領域]]
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-[[RFCのライセンス]]
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