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翻译：911
Network Working Group N. Freed
Request for Comments: 2045 Innosoft
Obsoletes: 1521, 1522, 1590 N. Borenstein
Category: Standards Track First Virtual
November 1996
Multipurpose Internet Mail Extensions
(MIME) Part One:
Format of Internet Message Bodies
通用互联网邮件扩展（MIME）第一部分：
互联网信息体格式
Status of this Memo
本备忘录状况
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.
本文档为互联网社团规定了一个互联网追踪协议的互联网标准，它需要进一步讨论和建议以得到改进。请查阅互联网正式协议标准（STD 1）最新版本来获得本协议的标准化状态和状况。本备忘录的发行是无约束的。
Abstract
摘要
STD 11, RFC 822, defines a message representation protocol specifying
considerable detail about US-ASCII message headers, and leaves the
message content, or message body, as flat US-ASCII text. This set of
documents, collectively called the Multipurpose Internet Mail
Extensions, or MIME, redefines the format of messages to allow for
STD 11,RFC 822,定义了一个信息请求协议，详细说明了大量的关于US-ASCII 信息报头的细节，并规定信息内容或者信息主体为US-ASCII文本。这一套文档共同被称为通用互联网邮件扩展，或者MIME,重新定义了虑及如下内容的信息格式：
(1) textual message bodies in character sets other than
US-ASCII,
（1）非US-ASCII的字符集文本信息主体，
(2) an extensible set of different formats for non-textual
message bodies,
（2）不同格式的非文本信息主体的扩展集，
(3) multi-part message bodies, and
(3)多部分的信息主体，
(4) textual header information in character sets other than
US-ASCII.
（4）非US-ASCII的字符集文本信息报头。
These documents are based on earlier work documented in RFC 934, STD
11, and RFC 1049, but extends and revises them. Because RFC 822 said
so little about message bodies, these documents are largely
orthogonal to (rather than a revision of) RFC 822.
这些文档是以早期的RFC 934,STD 11和RFC 1049的工作文档为基础，但有所扩展和修正。因为RFC 822 对于信息主体仅讲述了一点点，这些文档与RFC 822 迥异（不仅仅是修正RFC 822）
This initial document specifies the various headers used to describe
the structure of MIME messages. The second document, RFC 2046,
defines the general structure of the MIME media typing system and
defines an initial set of media types. The third document, RFC 2047,
describes extensions to RFC 822 to allow non-US-ASCII text data in
Internet mail header fields. The fourth document, RFC 2048, specifies
various IANA registration procedures for MIME-related facilities. The
fifth and final document, RFC 2049, describes MIME conformance
criteria as well as providing some illustrative examples of MIME
message formats, acknowledgements, and the bibliography.
本草签文档详细说明了用来描述MIME消息结构的各种各样的报头。第二份文档，RFC 2046,定义了MIME媒体类型系统的总体结构并定义了媒体类型的初始集。第三份文档，RFC 2047,它扩展了RFC 822以允许互联网邮件报头字段出现非US-ASCII文本数据。第四份文档，RFC 2048,详细说明了MIME相关设备的注册IANA（国际互联网地址分配委员会）的不同注册程序。第五个文档，也就是最后一个文档，RFC 2049,描述了MIME的一致性标准，也提供了一些说明性的关于MIME信息格式的示例，还有“感谢”和“参考书目”。
These documents are revisions of RFCs 1521, 1522, and 1590, which
themselves were revisions of RFCs 1341 and 1342. An appendix in RFC
2049 describes differences and changes from previous versions.
这些文档是RFCs 1521，1522和1590的修正，他们自己（译者注：他们是指RFCs 1521,1522和1590）是RFCs 1341和1342的修正。在RFC 2049的附录里描述了其与以前版本的不同和变化。
Table of Contents
目录
1. Introduction ......................................... 3
1. 介绍.................................................. 3
2. Definitions, Conventions, and Generic BNF Grammar .... 5
2. 定义, 协定, 一般 BNF语法 ............................. 5
2.1 CRLF ................................................ 5
2.1 CRLF ................................................ 5
2.2 Character Set ....................................... 6
2.2 字符集 .............................................. 6
2.3 Message ............................................. 6
2.3 信息 .. ............................................. 6
2.4 Entity .............................................. 6
2.4 实体 ................................................ 6
2.5 Body Part ........................................... 7
2.5 主体部分 ............................................ 7
2.6 Body ................................................ 7
2.6 主体 ................................................ 7
2.7 7bit Data ........................................... 7
2.7 七位的数据 .......................................... 7
2.8 8bit Data ........................................... 7
2.8 八位的数据 .......................................... 7
2.9 Binary Data ......................................... 7
2.9 二进制数据 .......................................... 7
2.10 Lines .............................................. 7
2.10 行 ................................................. 7
3. MIME Header Fields ................................... 8
3. MIME 头字段 .......................................... 8
4. MIME-Version Header Field ............................ 8
4. MIME-Version 头字段 .................................. 8
5. Content-Type Header Field ............................ 10
5. 内容类型字段 ......................................... 10
5.1 Syntax of the Content-Type Header Field ............. 12
5.1 内容类型头字段的语法 ................................ 12
5.2 Content-Type Defaults ............................... 14
5.2 内容类型默认值 ...................................... 14
6. Content-Transfer-Encoding Header Field ............... 14
6. 内容转换编码头字段 ................................... 14
6.1 Content-Transfer-Encoding Syntax .................... 14
6.1 内容转换编码的语法 .................................. 14
6.2 Content-Transfer-Encodings Semantics ................ 15
6.2 内容转换编码的语义 .................................. 15
6.3 New Content-Transfer-Encodings ...................... 16
6.3 新内容转换编码 ...................................... 16
6.4 Interpretation and Use .............................. 16
6.4 解释和使用 .......................................... 16
6.5 Translating Encodings ............................... 18
6.5 转换编码 ............................................ 18
6.6 Canonical Encoding Model ............................ 19
6.6 正则编码模型 ........................................ 19
6.7 Quoted-Printable Content-Transfer-Encoding .......... 19
6.7 引用可印刷的内容转换编码 ............................ 19
6.8 Base64 Content-Transfer-Encoding .................... 24
6.8 Base64 内容转换编码 ................................. 24
7. Content-ID Header Field .............................. 26
7. 内容ID头字段 ........................................ 26
8. Content-Description Header Field ..................... 27
8. 内容描述头字段 ....................................... 27
9. Additional MIME Header Fields ........................ 27
9. 附加的MIME头字段 .................................... 27
10. Summary ............................................. 27
10. 摘要 ................................................ 27
11. Security Considerations ............................. 27
11. 安全考虑 ............................................ 27
12. Authors' Addresses .................................. 28
12. 作者地址 ............................................ 28
A. Collected Grammar .................................... 29
A. 收集的语法 ........................................... 29