'''The MIME Multipart/Related Content-type'''
- Network Working Group
- [DEL(rfc2112)[Request for Comments: 1872]]
- [DEL(rfc2387)[[INS(rfc2112)[Request for Comments: 2112]]]]
- [INS(rfc2387)[Request for Comments: 2387                                  
- [DEL(rfc2112)[Category: Experimental]]     
- [DEL(rfc2387)[[INS(rfc2112)[Category: Standards Track]]
- [DEL(rfc2387)[[INS(rfc2112)[Obsoletes: 1872]]]]
- [INS(rfc2387)[Obsoletes: 2112]]
- [INS(rfc2387)[Category: Standards Track]]
- E. Levinson
- [DEL(rfc2112)[Accurate Information Systems, Inc.]]
- [DEL(rfc2387)[[INS(rfc2112)[XIson, Inc.]]]]
- [DEL(rfc2112)[December 1995]]
- [DEL(rfc2387)[[INS(rfc2112)[March 1997]]]]
- [INS(rfc2387)[August 1998]]

* Status of this Memo
[DEL(rfc2112)[
> This memo defines an Experimental Protocol for the Internet
community.  This memo does not specify an Internet standard of any
kind.  Discussion and suggestions for improvement are requested.
Distribution of this memo is unlimited.
]DEL]

[INS(rfc2112)[
> This document specifies an Internet standards track protocol for the
Internet community, and requests discussion and suggestions for
improvements.  Please refer to the current edition of the "Internet
Official Protocol Standards" (STD 1) for the standardization state
and status of this protocol.  Distribution of this memo is unlimited.
]INS]
  
* Copyright Notice
[INS(rfc2387)[
>   Copyright (C) The Internet Society (1998).  All Rights Reserved.
]INS]

* Abstract
>     The Multipart/Related content-type provides a common mechanism for
representing objects that are aggregates of related MIME body parts.
This document defines the Multipart/Related content-type and provides
examples of its use.
  
* 1.  Introduction
>     Several applications of MIME, including MIME-PEM, and MIME-Macintosh
and other proposals, require multiple body parts that make sense only
in the aggregate.  The present approach to these compound objects has
been to define specific multipart subtypes for each new object.  In
keeping with the MIME philosophy of having one mechanism to achieve
the same goal for different purposes, this document describes a
single mechanism for such aggregate or compound objects.

[[MIME]] [[PEM]] や [[MacMIME]] やその他の提案など幾つかの [[MIME]]
の[[応用]]は集積のためだけに複数[[本体部分]]を必要としています。
このような合成物体に現在採られているのは新しい物体それぞれに特定の多部分部分型を定義するという方法です。
この文書は、集積・合成物体のための、
異なる目的で同じ目標を達成するための1つの仕組みを持つという
[[MIME]] の精神を守った一つの仕組みを説明します。
 
>     The Multipart/Related content-type addresses the MIME representation
of compound objects.  The object is categorized by a "type"
parameter.  Additional parameters are provided to indicate a specific
starting body part or root and auxiliary information which may be
required when unpacking or processing the object.

[CODE(MIME)[[[multipart/related]]]] 内容型は合成物体の [[MIME]]
表現を表します。物体は [CODE(MIME)[[[type]]]]
引数により分類します。特定の開始[[本体部分]] ([[根]])
を示す引数や物体を取出し・処理する時に必要な補助情報のための引数も提供します。

[INS(rfc2112)[
> Multipart/Related MIME entities may contain Content-Disposition
headers that provide suggestions for the storage and display of a
body part.  Multipart/Related processing takes precedence over
Content-Disposition; the interaction between them is discussed in
section 4.

[CODE(MIME)[[[multipart/related]]]] [[MIME]] [[実体]]は本体部分の蓄積と表示に関する提案を行う
[CODE(MIME)[[[Content-Disposition]]]] 頭を含んでも構いません。
[CODE(MIME)[multipart/related]] 処理は [CODE(MIME)[Content-Disposition]]
より優先します。両者の関係は4章で議論します。
]INS]

>     Responsibility for the display or processing of a Multipart/Related's
constituent entities rests with the application that handles the
compound object.

[CODE(MIME)[multipart/related]] を構成する実体の表示・処理の責任は豪勢物体を扱う応用にあります。

*2.  Multipart/Related Registration Information
>    The following form is copied from RFC 1590, Appendix A.

次の書式は [[RFC 1590]] 附属書 A から複写しました。

> 
-   To:  IANA@isi.edu
-   Subject:  Registration of new Media Type content-type/subtype
>  
-     Media Type name:           Multipart
> 
-     Media subtype name:        Related
>  
-     Required parameters:       Type, a media type/subtype.
>  
-   Optional parameters:       Start[DEL(rfc2112)[, a content-id.]]
                              Start-info[DEL(rfc2112)[, a string or content-id list.]]
>
-     Encoding considerations:   Multipart content-types cannot have encodings.
>  
-     Security considerations:   Depends solely on the referenced type.
>  
-   Published specification:   [DEL(rfc2112)[This document.]] [INS(rfc2112)[RFC-REL (this document).]]
>  
-     Person & email address to contact for further information:
[PRE[
Edward Levinson
[DEL(rfc2112)[Accurate Information Systems, Inc.]]
[DEL(rfc2112)[2 Industrial Way]]
[DEL(rfc2112)[Eatontown, NJ 07724]]
[DEL(rfc2112)[+1 908 389 5550]]
[DEL(rfc2112)[+1 908 389 5556 (fax)]]
[DEL(rfc2112)[ELevinson@Accurate.com]]
[INS(rfc2112)[47 Clive Street]]
[INS(rfc2112)[Metuchen, NJ 08840-1060]]
[INS(rfc2112)[+1 908 494 1606]]
[INS(rfc2112)[XIson@cnj.digex.net]]
]PRE]

* 3.  Intended usage
>     The Multipart/Related media type is intended for compound objects
consisting of several inter-related body parts.  For a
Multipart/Related object, proper display cannot be achieved by
individually displaying the constituent body parts.  The content-type
of the Multipart/Related object is specified by the type parameter.
The "start" parameter, if given, points, via a content-ID, to the
body part that contains the object root.  The default root is the
first body part within the Multipart/Related body.

[CODE(MIME)[[[multipart/related]]]] [[媒体型]]は複数の関係のある[[本体部分]]から成る合成物体を想定しています。
[CODE(MIME)[multipart/related]] 物体では構成する本体部分を個々に表示するだけでは適切な表示とは言えません。
[CODE(MIME)[multipart/related]] 物体の内容型は [CODE(MIME)[[[type]]]]
引数で指定します。 [CODE(MIME)[[[start]]]] 引数があれば、
[[内容ID]] によって物体[[根]]を含む本体部分を表します。
既定の根は [CODE(MIME)[[[multipart/related]]]] [[本体]]の中の最初の本体部分です。

>     The relationships among the body parts of a compound object
distinguishes it from other object types.  These relationships are
often represented by links internal to the object's components that
reference the other components.  Within a single operating
environment the links are often file names, such links may be
represented within a MIME message using content-IDs or the value of
some other "Content-" header[INS(rfc2112)[s]].

合成物体の本体部分間の関係は他の物体型と異なります。
関係はよく物体の部品の内部で他の部品を指す[[連結]]で表現されます。
一つの操作環境の中では連結はしばしば[[ファイル名]]であり、
そのような連結は MIME メッセージ中では[[内容ID]]
や他の [CODE(MIME)[[[Content-[VAR[*]]]]]] 頭の値で表現されるかもしれません。

** 3.1.  The Type Parameter
>     The type parameter must be specified and its value is the MIME media
type of the [INS(rfc2112)["]]root[INS(rfc2112)["]] body part.  It permits a MIME user agent to
determine the content-type without reference to the enclosed body
part.  If the value of the type parameter and the root body part's
content-type differ then the User Agent's behavior is undefined.

[CODE(MIME)[[[type]]]] 引数は指定しなければならず、
その値は[Q[[[根]]]][[本体部分]]の [[MIME]]
[[媒体型]]です。この引数により MIME 
[[利用者エージェント]]は囲まれた[[本体部分]]を参照しなくても[[内容型]]を決定できます。
[CODE(MIME)[type]] 引数の値と根本体部分の内容型が異なる時の利用者エージェントの動作は未定義です。

[DEL(rfc2112)[
>   Note: Constraining the "type" parameter's value to an existing media
type allows the appropriate processing to be identified without
creating yet another hierarchy of registered types.  A possible
default action would have the MIME mail User Agent (MUA) to display
the "start" entity alone when it could process the media type as a
basic type but not as Multipart/Related.

注意: [CODE(MIME)[type]] 引数の値を既存の媒体型に制約することで、
新しい登録型階層を作らずに適切な処理を識別できます。
[[MIME]] [[メイル利用者エージェント]] ([[MUA]])
が[[媒体型]]を基本型としては処理できるものの
[CODE(MIME)[[[multipart/related]]]] としては処理できない時に
[CODE(MIME)[[[start]]]] 実体だけを表示するのを既定の動作ともできるでしょう。
]DEL]

**3.2.  The Start Parameter
>     The start parameter, if given, is the content-ID of the compound
object's [INS(rfc2112)["]]root[INS(rfc2112)["]].  If not present the [INS(rfc2112)["]]root[INS(rfc2112)["]] is the first body part in
the Multipart/Related entity.  The [INS(rfc2112)["]]root[INS(rfc2112)["]] is the element the
application[INS(rfc2112)[s]] processes first.

[CODE(MIME)[[[start]]]] 引数は、指定された場合、
合成物体の[Q[[[根]]]]の[[内容ID]] です。
存在しない場合[Q[[[根]]]]は [CODE(MIME)[[[multipart/related]]]]
実体の中の最初の[[本体部分]]です。[Q[[[根]]]]は最初に[[応用]]が処理する要素です。

[DEL(rfc2112)[
>  In the case of a Multipart/Alternative body part containing several
entities with identical content-IDs the start entity should be
selected using the Multipart/Alternative rules.

[CODE(MIME)[[[multipart/alternative]]]] [[本体部分]]の場合で複数の実体が同じ内容
ID を持っている時は、 [CODE(MIME)[multipart/alternative]]
の規則により開始実体を選択するべきです。

>   Note: The "start" parameter allows for types in which the root
element gets generated by the sending application, perhaps on the
fly.  Such an application can create the "start" content-id when
processing begins and then insert the body part when it is complete.

注意: [CODE(MIME)[start]] 引数は根要素が送信応用によりおそらくはその場で生成されるような型も認めます。
そのような応用は処理が始まる時に [CODE(MIME)[start]]
内容 ID を作成して、処理が完了してから本体部分を挿入することができます。
]DEL]

** 3.3.  The Start-Info Parameter
>     Additional information can be provided to an application by the
start-info parameter.  It contains either a string or points, via a
content-ID, to another MIME entity in the message.  A typical use
might be to provide additional command line parameters or a MIME
entity giving auxiliary information for processing the compound object.

応用は追加情報を [CODE(MIME)[[[start-info]]]]
引数で提供できます。この引数は文字列か内容 ID
によるメッセージ中の他の MIME 実体の参照のいずれかを含みます。
追加の命令行引数の提供や豪勢物体の処理のための補助情報を提供する
MIME 実体の指定が典型的な例です。

>     Applications that use Multipart/Related must specify the
interpretation of start-info.  User Agents shall provide the
parameter's value to the processing application.  Processes can
distinguish a start-info reference from a token or quoted-string by
examining the first non-white-space character, "<" indicates 
a [DEL(rfc2112)[content-id]] reference.

[CODE(MIME)[multipart/related]] を使う応用は [CODE(MIME)[[[start-info]]]]
の解釈を規定しなければなりません。利用者エージェントは引数値を処理応用に提供しなければなりません。
[CODE(MIME)[start-info]] の参照と字句や引用文字列は最初の非空白文字を調べれば区別できます。
最初の文字が [CODE[<]] であれば参照です。

** 3.4.  Syntax
>  
       related-param    := [ ";" "start" "=" cid ]
                           [ ";" "start-info"  "="
                             ( cid-list / value ) ]
                           [ ";" "type"  "=" type "/" subtype ]
                           ; order independent
>
       cid-list        := cid cid-list
>  
       cid             := msg-id     ; c.f. [822]
>
       value           := token / quoted-string    ; c.f. [MIME]
                               ; value cannot begin with "<"

>     Note that the parameter values will usually require quoting.  Msg-id
contains the special characters "<", ">", "@", and perhaps other
special characters.  If msg-id contains quoted-strings, those quote
marks must be escaped.  Similarly, the type parameter contains the
special character "/".

注意: 引数値は通常引用が必要です。 [CODE(ABNF)[[[msg-id]]]]
は特殊文字 [CODE[<]], [CODE[>]], [CODE[@]]
を含みますし、おそらく他の特殊文字も含むでしょう。 [CODE(ABNF)[msg-id]]
が引用文字列を含む場合、その引用符を逃避しなければなりません。
同様に、 [CODE(MIME)[type]] 引数は特殊文字 [CODE[/]]
を含みます。

* 4.  Handling Content-Disposition Headers
[INS(rfc2112)[
>  
Content-Disposition Headers [DISP] suggest presentation styles for
MIME body parts.  [DISP] describes two presentation styles, called
the disposition type, INLINE and ATTACHMENT.  These, used within a
multipart entity, allow the sender to suggest presentation
information.  [DISP] also provides for an optional storage (file)
name.  Content-Disposition headers could appear in one or more body
parts contained within a Multipart/Related entity.

[CODE(MIME)[[[Content-Disposition]]]] 頭は MIME
[[本体部分]]の表現様式を提案します。 [[RFC 1806]]
は表現様式を表す配置型として [CODE(MIME)[[[inline]]]], 
[CODE(MIME)[[[attachment]]]] の2種類を説明しています。
両者は[[多部分実体]]の中で使って、送信者が表現情報を提案することができます。
RFC 1806 は省略可能な蓄積域 (ファイル) 名も提供しています。
[CODE(MIME)[[[Content-Disposition]]]] 頭は 
[CODE(MIME)[[[multipart/related]]]] 実体に含まれる[[本体部分]]の一つ以上に出現できます。

>  
Using Content-Disposition headers in addition to Multipart/Related
provides presentation information to User Agents that do not
recognize Multipart/Related.  They will treat the multipart as
Multipart/Mixed and they may find the Content-Disposition information
useful.

[CODE(MIME)[[[multipart/related]]]] で
[CODE(MIME)[[[Content-Disposition]]]] 
も使うと [CODE(MIME)[multipart/related]] を認識しない[[利用者エージェント]]に表現情報を提供することができます。
認識しない利用者エージェントは多部分を [CODE(MIME)[[[multipart/mixed]]]]
として扱い、 [CODE(MIME)[[[Content-Disposition]]]]
情報を役立てるかもしれません。

>
With Multipart/Related however, the application processing the
compound object determines the presentation style for all the
contained parts.  In that context the Content-Disposition header
information is redundant or even misleading.  Hence, User Agents that
understand Multipart/Related shall ignore the disposition type within
a Multipart/Related body part.

しかし、 [CODE(MIME)[[[multipart/related]]]]
では合成物体を処理する[[応用]]が含まれている[[部分]]すべての表現様式を決定します。
そのため [CODE(MIME)[[[Content-Disposition]]]] 頭の情報は冗長だったり誤解の虞もあったりします。
ですから、 [CODE(MIME)[[[multipart/related]]]]
を理解する利用者エージェントは [CODE(MIME)[[[multipart/related]]]]
[[本体部分]]内の配置型を無視しなければなりません。

>
It may be possible for a User Agent capable of handling both
Multipart/Related and Content-Disposition headers to provide the
invoked application the Content-Disposition header's optional
filename parameter to the Multipart/Related.  The use of that
information will depend on the specific application and should be
specified when describing the handling of the corresponding compound
object.  Such descriptions would be appropriate in an RFC registering
that object's media type.

[CODE(MIME)[[[multipart/related]]]] と
[CODE(MIME)[[[Content-Disposition]]]] 頭の両方を扱うことのできる[[利用者エージェント]]は呼出す[[応用]]に
[CODE(MIME)[[[multipart/related]]]] の [CODE(MIME)[[[Content-Disposition]]]]
頭の省略可能な [CODE(MIME)[[[filename]]]] 引数を提供することも可能でしょう。
この情報を使うかは各応用に依存し、対応する合成物体の扱いを説明する時に規定するべきです。
その説明は物体の[[媒体型]]を登録する [[RFC]]
で行うのが適切でしょう。

*[DEL(rfc2112)[4.]] [INS(rfc2112)[5.]]  Examples
**[DEL(rfc2112)[4.1]] [INS(rfc2112)[5.1]] Application/X-FixedRecord
> The X-FixedRecord content-type consists of one or more octet-streams
and a list of the lengths of each record.  The root, which lists the
record lengths of each record within the streams.  The record length
list, type Application/X-FixedRecord, consists of a set of INTEGERs
in ASCII format, one per line.  Each INTEGER gives the number of
octets from the octet-stream body part that constitute the next "record".

[SAMP(MIME)[x-fixedrecord]] 内容型は一つ以上のオクテット列と各[[記録]]の長さの[[並び]]から成ります。
根はオクテット列中の各記録の長さを列挙します。
[CODE(MIME)[application/x-fixedrecord]] 型の記録長並びは [[ASCII]]
書式の行毎の整数の連続で構成します。各整数はオクテット列本体部分の次の
[Q[記録]]のオクテット数を表します。

>
The example below, uses a single data block [DEL(rfc2112)[which the sender processes on the fly to generate the record length list]]. [DEL(rfc2112)[Consequently the list appears after the data.]]

次の例は1つのデータ塊を表します。

>
[PRE[
Content-Type: Multipart/Related; boundary=example-1
        start="<950120.aaCC@XIson.com>";
        type="Application/X-FixedRecord"
        start-info="-o ps"

[INS(rfc2112)[--example-1]]
[INS(rfc2112)[Content-Type: Application/X-FixedRecord]]
[INS(rfc2112)[Content-ID: <950120.aaCC@XIson.com>]]
[INS(rfc2112)[]]
[INS(rfc2112)[25]]
[INS(rfc2112)[10]]
[INS(rfc2112)[34]]
[INS(rfc2112)[10]]
[INS(rfc2112)[25]]
[INS(rfc2112)[21]]
[INS(rfc2112)[26]]
[INS(rfc2112)[10]]
--example-1
Content-Type: Application/octet-stream
Content-Description: The fixed length records
Content-Transfer-Encoding: base64
Content-ID: <950120.aaCB@XIson.com>

T2xkIE1hY0RvbmFsZCBoYWQgYSBmYXJtCkUgSS
BFIEkgTwpBbmQgb24gaGlzIGZhcm0gaGUgaGFk
IHNvbWUgZHVja3MKRSBJIEUgSSBPCldpdGggYS
BxdWFjayBxdWFjayBoZXJlLAphIHF1YWNrIHF1
YWNrIHRoZXJlLApldmVyeSB3aGVyZSBhIHF1YW
NrIHF1YWNrCkUgSSBFIEkgTwo=
[DEL(rfc2112)[--example-1]]
[DEL(rfc2112)[Content-Type: Application/X-FixedRecord]]
[DEL(rfc2112)[Content-ID: <950120.aaCC@XIson.com>]]
[DEL(rfc2112)[]]
[DEL(rfc2112)[25]]
[DEL(rfc2112)[10]]
[DEL(rfc2112)[34]]
[DEL(rfc2112)[10]]
[DEL(rfc2112)[25]]
[DEL(rfc2112)[21]]
[DEL(rfc2112)[26]]
[DEL(rfc2112)[10]]
--example-1--
]PRE]

**[DEL(rfc2112)[4.2]] [INS(rfc2112)[5.2]] Text/X-Okie
>
The Text/X-Okie is an invented markup language[DEL(rfc2112)[, similar to HTML, that permits]] [INS(rfc2112)[permitting]] the
inclusion of images with text.  A feature of this example is the
inclusion of two additional body parts, both picture. They are
referred to internally by the encapsulated document via each
picture's body part content-ID.  Usage of "cid:", as in this example,
may be useful for a variety of compound objects.  It is not, however,
a part of the Multipart/Related specification.

[SAMP(MIME)[text/x-okie]] は架空の[[マーク付け言語]]で、
文章に画像を含めることができます。この例では2つの画像の[[本体部分]]が含まれています。
本体部分はカプセル化された文書から画像の本体部分の内容
ID で内部的に参照されています。この例のように
[SAMP(URI)[[[cid]]:]] を使うのは色々な合成物体で便利でしょう。
しかし、これは [CODE(MIME)[[[multipart/related]]]]
仕様の一部ではありません。

>
[PRE[
Content-Type: Multipart/Related; boundary=example-2;
        start="<950118.AEBH@XIson.com>"
        type="Text/x-Okie"

--example-2
Content-Type: Text/x-Okie; charset=iso-8859-1;
        declaration="<950118.AEB0@XIson.com>"
Content-ID: <950118.AEBH@XIson.com>
Content-Description: Document

{doc}
This picture was taken by an automatic camera mounted ...
{image file=cid:[DEL(rfc2387)[[INS(rfc2112)[<]]]]950118.AECB@XIson.com[DEL(rfc2387)[[INS(rfc2112)[>]]]]}
{para}
Now this is an enlargement of the area ...
{image file=cid:[DEL(rfc2387)[[INS(rfc2112)[<]]]]950118:AFDH@XIson.com[DEL(rfc2387)[[INS(rfc2112)[>]]]]}
{/doc}
--example-2
Content-Type: image/jpeg
Content-ID: <950118.AFDH@XIson.com>
Content-Transfer-Encoding: BASE64
Content-Description: Picture A

[encoded jpeg image]
--example-2
Content-Type: image/jpeg
Content-ID: <950118.AECB@XIson.com>
Content-Transfer-Encoding: BASE64
Content-Description: Picture B

[encoded jpeg image]
--example-[DEL(rfc2112)[1]][INS(rfc2112)[2]]--
]PRE]

**5.3 Content-Disposition
[INS(rfc2112)[
>   In the above example each image body part could also have a 
Content-Disposition header.  For example,

先の例で各画像本体部分に [CODE(MIME)[[[Content-Disposition]]]]
頭も付けることができます。

>
[PRE[
[DEL(rfc2387)[...]]
--example-2
Content-Type: image/jpeg
Content-ID: <950118.AECB@XIson.com>
Content-Transfer-Encoding: BASE64
Content-Description: Picture B
Content-Disposition: INLINE

[encoded jpeg image]
--example-2--
]PRE]

>   User Agents that recognize Multipart/Related will ignore the
Content-Disposition header's disposition type.  Other User Agents
will process the Multipart/Related as Multipart/Mixed and may make
use of that header's information.

[CODE(MIME)[multipart/related]]
を認識する[[利用者エージェント]]は [CODE(MIME)[[[Content-Disposition]]]]
頭の配置型を無視します。他の利用者エージェントは
[CODE(MIME)[[[multipart/related]]]] を
[CODE(MIME)[[[multipart/mixed]]]] として処理し、
[CODE(MIME)[[[Content-Disposition]]]] 頭の情報も利用するかもしれません。
]INS]

* [DEL(rfc2112)[5.]] [INS(rfc2387)[6.]]  User Agent Requirements
>    User agents that do not recognize Multipart/Related shall, in
accordance with [MIME], treat the entire entity as Multipart/Mixed.
MIME User Agents that [INS(rfc2112)[do]] recognize Multipart/Related entities but are
unable to process the given type [DEL(rfc2112)[shall either suppress the entire Multipart/Related body part or process the root alone]] [INS(rfc2112)[should give the user the option of suppressing the entire Multipart/Related body part shall be. [DEL(rfc2112)[In either case the user should be notified of the MUA's action.]]

[CODE(MIME)[[[multipart/related]]]] を認識しない[[利用者エージェント]]は
[[MIME]] に従い実体全体を [CODE(MIME)[[[multipart/mixed]]]]
として扱います。 MIME 利用者エージェントで [CODE(MIME)[[[multipart/related]]]]
実体を認識するものの与えられた [CODE(MIME)[[[type]]]]
を処理できないものは、 [CODE(MIME)[[[multipart/related]]]]
本体部分全体を抑制する選択肢を利用者に提供するべきです。

> [INS(rfc2112)[Existing MIME-capable mail user agents (MUAs) handle the existing media types in a straightforward manner.  For discrete media types (e.g. text, image, etc.) the body of the entity can be directly passed to a display process.  Similarly the existing composite subtypes can be reduced to handing one or more discrete types.]]
Handling Multipart/Related differs [DEL(rfc2112)[from other media types]] in that
processing cannot be reduced to handling the individual entities. [DEL(rfc2112)[Existing media types are handled by MIME-capable MUAs handle in a straightforward manner.  For basic media types (e.g., text, image, etc.) the body of the entity can be directly passed to a display process.  Composite media types can be reduced to handing one or more discrete types.]]

既存の MIME メイル利用者エージェントは既存の媒体型をそのままの方法で扱います。
分離媒体型 (例えば [CODE(MIME)[[[text/[VAR[*]]]]]],
[CODE(MIME)[[[image/[VAR[*]]]]]] など) は実体の本体を直接表示処理に渡すことができます。
同様に既存の合成部分型は一つ以上の分離型として扱うことができます。
[CODE(MIME)[multipart/related]] の扱いは処理を個々の実体に分けることができないという点が異なります。

[DEL(rfc2112)[
> Multipart/Related provides an irreducible composite media type.
]DEL]

>     The following sections discuss what information the processing
application requires.

次の節では処理応用がどんな情報が必要かを議論します。

>
It is possible that an application specific "receiving agent" will
manipulate the entities[DEL(rfc2112)[, after initial processing by the MIME User Agent,]] [INS(rfc2112)[for display]] prior to invoking actual
application process. [DEL(rfc2112)[From the viewpoint of the MUA, the receiving agent is the application.]]
Okie, above, [DEL(rfc2112)[demonstrates]] [INS(rfc2112)[is an example of]] this; it may need
a receiving agent to parse the document and substitute local file
names for the originator's file names.  Other applications may just
require a table showing the correspondence between the local file
names and the originator's.  [INS(rfc2112)[The receiving agent takes responsibility for such processing.]]

応用規定の[Q[受信エージェント]]が実際の応用処理を呼出す前に実体を走査することも可能です。
先の Okie はこの例で、受信エージェントは文書を構文解析し、
局所ファイル名を送信者側のファイル名に書き換えます。
他の応用はただ単に局所ファイル名と受信者のファイル名の対応表が必要かもしれません。
受信エージェントはこのような処理の責任を持ちます。

[DEL(rfc2112)[
> The receiving agent takes responsibility any for such processing.
]DEL]

**[DEL(rfc2112)[5.1]] [INS(rfc2112)[6.1]] Data Requirements
>
MIME-capable [DEL(rfc2112)[MUAs]] [INS(rfc2112)[mail user agents (MUAs)]]
are required to provide the

MIME メイル利用者エージェントは次のものを提供する必要があります。

>
- (a) the bodies of the MIME entities and the entity Content-* headers,
- (b) the parameters of the Multipart/Related Content-type header, and
- (c) the correspondence between each body's local file name, that
body's header data, and, if present, the body part's content-ID.

- MIME 実体の[[本体]]と実体の [CODE(MIME)[[[Content-[VAR[*]]]]]] 頭
- [CODE(MIME)[[[multipart/related]]]] [CODE(MIME)[[[Content-Type]]]] 頭
- 各本体の局所ファイル名、本体の頭データ、あれば本体部分の内容 ID
の間の対応

** [DEL(rfc2112)[5.2]] [INS(rfc2112)[6.2]] Storing Multipart/Related Entities
>     The Multipart/Related media type will be used for objects that have
internal linkages between the body parts.  When the objects are
stored the linkages may require processing by the application or its
receiving agent.

[CODE(MIME)[[[multipart/related]]]] 媒体型は本体部分間の内部連結を持つ物体に使われます。
物体が蓄積される時に応用やその樹脂ねーじぇんとが連結を処理する必要があるかもしれません。

**[DEL(rfc2112)[5.3]] [INS(rfc2112)[6.3]] Recursion
>     MIME is a recursive structure.  Hence one must expect a
Multipart/Related entity to contain other Multipart/Related entities.
When a Multipart/Related entity is being processed for display or
storage, any enclosed Multipart/Related entities shall be processed
as though they were being stored.  [DEL(rfc2112)[It shall be the responsibility of the application handling the outermost Multipart/Related to insure the appropriate processing of embedded Multipart/Related entities.]]

MIME は再帰的構造です。ですから [CODE(MIME)[multipart/related]]
実体が別の [CODE(MIME)[multipart/related]] 実体を含んでいることを想定しなければなりません。
[CODE(MIME)[multipart/related]] 実体が表示や蓄積のため処理される時、
囲まれた [CODE(MIME)[multipart/related]] 実体は蓄積されているものであるかのように処理しなければなりません。

** [DEL(rfc2112)[5.5]] [INS(rfc2112)[6.4]] Configuration Considerations
>     It is suggested that MUAs that use configuration mechanisms, 
see [CFG] for an example, refer to Multipart/Related as
Multipart/Related/<type>, were <type> is the value of the "type" parameter.

MUA は設定機構を使う場合 [CODE(MIME)[multipart/related]]
を指すのに [SAMP[Multipart/Related/[VAR[<type>]]]]
([VAR[<type>]] は [CODE(MIME)[type]] 引数の値)
のようにすることを提案します。

**[DEL(rfc2112)[6.]] [INS(rfc2112)[7.]]  Security considerations
>     Security considerations relevant to Multipart/Related are identical
to those of the underlying content-type.

[CODE(MIME)[multipart/related]] に関係する安全上の考慮点は使用する内容型と同じでうs。

*[DEL(rfc2112)[7.]] [INS(rfc2112)[8.]]  Acknowledgments
>     This proposal is the result of conversations the author has had with
many people.  In particular, [DEL(rfc2112)[similar work was described by]]
Harald A.
Alvestrand [DEL(rfc2112)[(early drafts of Multipart/Related), Dave Crocker (Multipart/Families), and Keith Moore (Multipart/References). In addition,]]
James Clark, Charles Goldfarb, Gary Houston, Ned Freed, Ray Moody, and Don
Stinchfield, provided both encouragement and invaluable help.  The
author, however, take full responsibility for all errors contained in
this document.

*[DEL(rfc2112)[8.]] [INS(rfc2112)[9.]]  References

>
[822]       Crocker, D., "Standard for the Format of ARPA Internet
Text Messages", [DEL(rfc2112)[STD 11, RFC 822, UDEL, August 1982]] [DEL(rfc2387)[[INS(rfc2112)[August 1982, University of Delaware, RFC 822]]]] [INS(rfc2387)[STD 11, RFC 822, August 1982]].

[INS(rfc2112)[
>
[CID]       [DEL(rfc2387)[E. Levinson]] [INS(rfc2387)[Levinson, E., and]] J. Clark, "Message/External-Body
Content-ID Access Type", [DEL(rfc2387)[12/26/1995,]] RFC 1873 [INS(rfc2387)[December 1995,]]
Levinson, E., "Message/External-Body Content-ID Access Type", [DEL(rfc2387)[February 1997, RFC 2111]] [INS(rfc2387)[Work in Progress]].
]INS]

>
[CFG]       Borenstein, N., "A User Agent Configuration Mechanism For
Multimedia Mail Format Information", [DEL(rfc2112)[RFC 1524,]] [INS(rfc2387)[RFC 1524,]] [DEL(rfc2112)[Bellcore,]]
September [DEL(rfc2387)[[INS(rfc2112)[23,]]]] 
1993[DEL(rfc2387)[, RFC 1524]][INS(rfc2387)[.]]

[INS(rfc2112)[
>
[DISP]      [DEL(rfc2387)[R. Troost,]] [INS(rfc2387)[Troost, R., and]] S. Dorner, "Communicating Presentation
Information in Internet Messages:  The Content-Disposition Header", [DEL(rfc2387)[June 7, 1995, RFC 1806]] [INS(rfc2387)[RFC 1806, June 1995.]]

>
[MIME]      Borenstein, N.[INS(rfc2387)[,]] and [DEL(rfc2112)[and N. Freed]] [INS(rfc2112)[Freed, N.]], [DEL(rfc2387)["MIME (Multipurpose Internet Mail Extensions) [DEL(rfc2112)[Part One]]: Mechanisms for Specifying and Describing the Format of Internet Message Bodies", [DEL(rfc2112)[RFC 1521, Bellcore, Innosoft, September 1993]] [INS(rfc2112)[June 1992, RFC 1341]]]] [INS(rfc2387)["Multipurpose Internet Mail Extensions (MIME) Part One: Format of Internet Message Bodies", RFC 2045, November 1996]].

* 9.  Author's Address
>  
   Edward Levinson
   [DEL(rfc2112)[Accurate Information Systems, Inc.]]
   [DEL(rfc2112)[2 Industrial Way]]
   [DEL(rfc2112)[Eatontown, NJ  07724-2265]]
   [DEL(rfc2387)[[INS(rfc2112)[XIson, Inc.]]]]
   [INS(rfc2112)[47 Clive Street]]
   [INS(rfc2112)[Metuchen, NJ  08840-1060]]
   USA

   [DEL(rfc2112)[Phone: +1 908 389 5550]]
   [DEL(rfc2387)[[INS(rfc2112)[+1 908 549 3716]]]]
   [INS(rfc2387)[Phone: +1 908 494 1606]]
   [DEL(rfc2112)[EMail: ELevinson@Accurate.com]]
   [DEL(rfc2387)[[INS(rfc2112)[<XIson@cnj.digex.com>]]]]
   [INS(rfc2387)[EMail: XIson@cnj.digex.com]]

*10.  Changes from previous draft (RFC 2112)
> Corrected cid urls to conform to RFC 2111; the angle brackets were removed.

*11.  Full Copyright Statement
[INS(rfc2387)[
> Copyright (C) The Internet Society (1998).  All Rights Reserved.
> This document and translations of it may be copied and furnished to
others, and derivative works that comment on or otherwise explain it
or assist in its implementation may be prepared, copied, published
and distributed, in whole or in part, without restriction of any
kind, provided that the above copyright notice and this paragraph are
included on all such copies and derivative works.  However, this
document itself may not be modified in any way, such as by removing
the copyright notice or references to the Internet Society or other
Internet organizations, except as needed for the purpose of
developing Internet standards in which case the procedures for
copyrights defined in the Internet Standards process must be
followed, or as required to translate it into languages other than English.
> The limited permissions granted above are perpetual and will not be
revoked by the Internet Society or its successors or assigns.
> This document and the information contained herein is provided on an
"AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
]INS]

*memo

[1] 第2版 ([[RFC 2112]]) は編集上のおかしな点 (謎の空白とか、
参考文献が第1版が参照しているものより古い版に戻っているとか)
が多々あります。多くは第3版 ([[RFC 2387]]) で修正されていますが、
直っていない点 (参考文献の章の番号) もあります。