draft-ietf-appsawg-xml-mediatypes-02.txt   draft-ietf-appsawg-xml-mediatypes-03.txt 
Network Working Group C. Lilley Network Working Group H. S. Thompson
Internet-Draft W3C Internet-Draft University of Edinburgh
Obsoletes: 3023 (if approved) M. Murata Obsoletes: 3023 (if approved) C. Lilley
Updates: 4289, 6839 (if approved) International University of Japan Updates: 6839 (if approved) W3C
Intended status: Standards Track A. Melnikov Intended status: Standards Track October 16, 2013
Expires: January 09, 2014 Isode Ltd. Expires: April 19, 2014
H. S. Thompson
University of Edinburgh
July 08, 2013
XML Media Types XML Media Types
draft-ietf-appsawg-xml-mediatypes-02 draft-ietf-appsawg-xml-mediatypes-03
Abstract Abstract
This specification standardizes three media types -- application/xml, This specification standardizes three media types -- application/xml,
application/xml-external-parsed-entity, and application/xml-dtd -- application/xml-external-parsed-entity, and application/xml-dtd --
for use in exchanging network entities that are related to the for use in exchanging network entities that are related to the
Extensible Markup Language (XML) while defining text/xml and text/ Extensible Markup Language (XML) while defining text/xml and text/
xml-external-parsed-entity as aliases for the respective application/ xml-external-parsed-entity as aliases for the respective application/
types. This specification also standardizes a convention (using the types. This specification also standardizes the '+xml' suffix for
suffix '+xml') for naming media types outside of these five types naming media types outside of these five types when those media types
when those media types represent XML MIME entities. represent XML MIME entities.
Major differences from [RFC3023] are alignment of charset handling
for text/xml and text/xml-external-parsed-entity with application/
xml, the addition of XPointer and XML Base as fragment identifiers
and base URIs, respectively, mention of the XPointer Registry, and
updating of many references.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on January 09, 2014. This Internet-Draft will expire on April 19, 2014.
Copyright Notice Copyright Notice
Copyright (c) 2013 IETF Trust and the persons identified as the Copyright (c) 2013 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Notational Conventions . . . . . . . . . . . . . . . . . . . 3 2. Notational Conventions . . . . . . . . . . . . . . . . . . . 3
3. XML Media Types . . . . . . . . . . . . . . . . . . . . . . . 4 3. XML Media Types . . . . . . . . . . . . . . . . . . . . . . . 4
3.1. Application/xml Registration . . . . . . . . . . . . . . 6 3.1. Application/xml Registration . . . . . . . . . . . . . . 5
3.2. Text/xml Registration . . . . . . . . . . . . . . . . . . 8 3.2. Text/xml Registration . . . . . . . . . . . . . . . . . . 7
3.3. Application/xml-external-parsed-entity Registration . . . 8 3.3. Application/xml-external-parsed-entity Registration . . . 7
3.4. Text/xml-external-parsed-entity Registration . . . . . . 9 3.4. Text/xml-external-parsed-entity Registration . . . . . . 8
3.5. Application/xml-dtd Registration . . . . . . . . . . . . 9 3.5. Application/xml-dtd Registration . . . . . . . . . . . . 8
3.6. Charset considerations . . . . . . . . . . . . . . . . . 10 3.6. Charset considerations . . . . . . . . . . . . . . . . . 9
3.6.1. Background . . . . . . . . . . . . . . . . . . . . . 11 4. The Byte Order Mark (BOM) and Charset Conversions . . . . . . 10
4. The Byte Order Mark (BOM) and Conversions to/from the UTF-16 5. Fragment Identifiers . . . . . . . . . . . . . . . . . . . . 11
Charset . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 6. The Base URI . . . . . . . . . . . . . . . . . . . . . . . . 12
5. Fragment Identifiers . . . . . . . . . . . . . . . . . . . . 12
6. The Base URI . . . . . . . . . . . . . . . . . . . . . . . . 13
7. XML Versions . . . . . . . . . . . . . . . . . . . . . . . . 13 7. XML Versions . . . . . . . . . . . . . . . . . . . . . . . . 13
8. A Naming Convention for XML-Based Media Types . . . . . . . . 13 8. A Naming Convention for XML-Based Media Types . . . . . . . . 13
8.1. Referencing . . . . . . . . . . . . . . . . . . . . . . . 15 8.1. Referencing . . . . . . . . . . . . . . . . . . . . . . . 14
8.2. +xml Structured Syntax Suffix Registration . . . . . . . 15 8.2. +xml Structured Syntax Suffix Registration . . . . . . . 15
9. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 16 9. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 16
9.1. UTF-8 Charset . . . . . . . . . . . . . . . . . . . . . . 17 9.1. UTF-8 Charset . . . . . . . . . . . . . . . . . . . . . . 17
9.2. UTF-16 Charset . . . . . . . . . . . . . . . . . . . . . 17 9.2. UTF-16 Charset . . . . . . . . . . . . . . . . . . . . . 17
9.3. Omitted Charset and 8-bit MIME entity . . . . . . . . . . 18 9.3. Omitted Charset and 8-bit MIME entity . . . . . . . . . . 17
9.4. Omitted Charset and 16-bit MIME entity . . . . . . . . . 18 9.4. Omitted Charset and 16-bit MIME entity . . . . . . . . . 18
9.5. Omitted Charset, no Internal Encoding Declaration and 9.5. Omitted Charset, no Internal Encoding Declaration and
UTF-8 Entity . . . . . . . . . . . . . . . . . . . . . . 19 UTF-8 Entity . . . . . . . . . . . . . . . . . . . . . . 18
9.6. UTF-16BE Charset . . . . . . . . . . . . . . . . . . . . 19 9.6. UTF-16BE Charset . . . . . . . . . . . . . . . . . . . . 19
9.7. Non-UTF Charset . . . . . . . . . . . . . . . . . . . . . 19 9.7. Non-UTF Charset . . . . . . . . . . . . . . . . . . . . . 19
9.8. Omitted Charset with Internal Encoding Declaration . . . 20 9.8. Omitted Charset with Internal Encoding Declaration . . . 19
9.9. INCONSISTENT EXAMPLE: Conflicting Charset and Internal 9.9. INCONSISTENT EXAMPLE: Conflicting Charset and Internal
Encoding Declaration . . . . . . . . . . . . . . . . . . 20 Encoding Declaration . . . . . . . . . . . . . . . . . . 20
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 20 9.10. INCONSISTENT EXAMPLE: Conflicting Charset and BOM . . . . 20
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 21
11. Security Considerations . . . . . . . . . . . . . . . . . . . 21 11. Security Considerations . . . . . . . . . . . . . . . . . . . 21
12. References . . . . . . . . . . . . . . . . . . . . . . . . . 22 12. References . . . . . . . . . . . . . . . . . . . . . . . . . 22
12.1. Normative References . . . . . . . . . . . . . . . . . . 23 12.1. Normative References . . . . . . . . . . . . . . . . . . 22
12.2. Informative References . . . . . . . . . . . . . . . . . 24 12.2. Informative References . . . . . . . . . . . . . . . . . 24
Appendix A. Why Use the '+xml' Suffix for XML-Based MIME Types? 25 Appendix A. Why Use the '+xml' Suffix for XML-Based MIME Types? 26
Appendix B. Changes from RFC 3023 . . . . . . . . . . . . . . . 25 Appendix B. Changes from RFC 3023 . . . . . . . . . . . . . . . 26
Appendix C. Acknowledgements . . . . . . . . . . . . . . . . . . 26 Appendix C. Acknowledgements . . . . . . . . . . . . . . . . . . 26
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 26 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 26
1. Introduction 1. Introduction
The World Wide Web Consortium has issued the Extensible Markup The World Wide Web Consortium has issued the Extensible Markup
Language (XML) 1.0 [XML] and Extensible Markup Language (XML) 1.1 Language (XML) 1.0 [XML] and Extensible Markup Language (XML) 1.1
[XML1.1] specifications. To enable the exchange of XML network [XML1.1] specifications. To enable the exchange of XML network
entities, this specification standardizes three media types -- entities, this specification standardizes three media types --
application/xml, application/xml-external-parsed-entity, and application/xml, application/xml-external-parsed-entity, and
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identifying XML-based MIME media types (using '+xml'). identifying XML-based MIME media types (using '+xml').
XML has been used as a foundation for other media types, including XML has been used as a foundation for other media types, including
types in every branch of the IETF media types tree. To facilitate types in every branch of the IETF media types tree. To facilitate
the processing of such types, and in line with the recognition in the processing of such types, and in line with the recognition in
[RFC6838] of structured syntax name suffixes, a suffix of '+xml' is [RFC6838] of structured syntax name suffixes, a suffix of '+xml' is
described in Section 8. This will allow generic XML-based tools -- described in Section 8. This will allow generic XML-based tools --
browsers, editors, search engines, and other processors -- to work browsers, editors, search engines, and other processors -- to work
with all XML-based media types. with all XML-based media types.
This specification replaces [RFC3023]. Major differences are in the
areas of alignment of charset handling for text/xml and text/xml-
external-parsed-entity with application/xml, the addition of XPointer
and XML Base as fragment identifiers and base URIs, respectively,
integration of the XPointer Registry and updating of many references.
2. Notational Conventions 2. Notational Conventions
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
specification are to be interpreted as described in [RFC2119]. specification are to be interpreted as described in [RFC2119].
As defined in [RFC2781] (informative), the three charsets "utf-16", As defined in [RFC2781] (informative), the three character sets
"utf-16le", and "utf-16be" are used to label UTF-16 text. In this "utf-16", "utf-16le", and "utf-16be" are used to label UTF-16 text.
specification, "the UTF-16 family" refers to those three charsets. In this specification, "the UTF-16 family" refers to those three
By contrast, the phrases "utf-16" or UTF-16 in this specification character sets. By contrast, the phrases "utf-16" or UTF-16 in this
refer specifically to the single charset "utf-16". specification refer specifically to the single charset "utf-16".
As sometimes happens between two communities, both MIME and XML have As sometimes happens between two communities, both MIME and XML have
defined the term entity, with different meanings. Section 2.4 of defined the term entity, with different meanings. Section 2.4 of
[RFC2045] says: [RFC2045] says:
"The term 'entity' refers specifically to the MIME-defined header "The term 'entity' refers specifically to the MIME-defined header
fields and contents of either a message or one of the parts in the fields and contents of either a message or one of the parts in the
body of a multipart entity." body of a multipart entity."
Section 4 of [XML] says: Section 4 of [XML] says:
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In this specification, "XML MIME entity" is defined as the latter (an In this specification, "XML MIME entity" is defined as the latter (an
XML entity) encapsulated in the former (a MIME entity). XML entity) encapsulated in the former (a MIME entity).
Furthermore, XML provides for the naming and referencing of entities Furthermore, XML provides for the naming and referencing of entities
for purposes of inclusion and/or substitution. In this specification for purposes of inclusion and/or substitution. In this specification
"XML-entity declaration/reference/..." is used to avoid confusion "XML-entity declaration/reference/..." is used to avoid confusion
when referring to such cases. when referring to such cases.
3. XML Media Types 3. XML Media Types
This specification standardizes three media types related to XML MIME Registration information for media types for use with XML MIME
entities: application/xml (with text/xml as an alias), application/ entities is described in the sections below. Within the XML
xml-external-parsed-entity (with text/xml-external-parsed-entity as specification, such entities can be classified into four types. In
an alias), and application/xml-dtd. Registration information for the XML terminology, they are called "document entities", "external
these media types is described in the sections below. DTD subsets", "external parsed entities", and "external parameter
entities". Appropriate usage for the types registered below is as
Within the XML specification, XML MIME entities can be classified follows:
into four types. In the XML terminology, they are called "document
entities", "external DTD subsets", "external parsed entities", and
"external parameter entities". Appropriate usage for these types is
as follows:
document entities The media types application/xml or text/xml MAY be document entities The media types application/xml or text/xml MAY be
used used.
external DTD subsets The media type application/xml-dtd SHOULD be external DTD subsets The media type application/xml-dtd SHOULD be
used. The media types application/xml and text/xml MUST NOT be used. The media types application/xml and text/xml MUST NOT be
used. used.
external parsed entities application/xml-external-parsed-entity or external parsed entities The media types application/xml-external-
text/xml-external-parsed-entity SHOULD be used. The media types parsed-entity or text/xml-external-parsed-entity SHOULD be used.
application/xml and text/xml MUST NOT be used unless the parsed The media types application/xml and text/xml MUST NOT be used
entities are also well-formed "document entities" and are unless the parsed entities are also well-formed "document
referenced as such. entities" and are referenced as such.
external parameter entities The media type application/xml-dtd external parameter entities The media type application/xml-dtd
SHOULD be used. The media types application/xml and text/xml MUST SHOULD be used. The media types application/xml and text/xml MUST
NOT be used. NOT be used.
Note that [RFC3023] (which this specification obsoletes) Note that [RFC3023] (which this specification obsoletes)
recommended the use of text/xml and text/xml-external-parsed- recommended the use of text/xml and text/xml-external-parsed-
entity for document entities and external parsed entities, entity for document entities and external parsed entities,
respectively, but described charset handling which differed from respectively, but described charset handling which differed from
common implementation practice. These media types are still common implementation practice. These media types are still
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and text/xml to be used for any of the four types, although in and text/xml to be used for any of the four types, although in
practice it is likely to have been rare. practice it is likely to have been rare.
Neither external DTD subsets nor external parameter entities parse as Neither external DTD subsets nor external parameter entities parse as
XML documents, and while some XML document entities may be used as XML documents, and while some XML document entities may be used as
external parsed entities and vice versa, there are many cases where external parsed entities and vice versa, there are many cases where
the two are not interchangeable. XML also has unparsed entities, the two are not interchangeable. XML also has unparsed entities,
internal parsed entities, and internal parameter entities, but they internal parsed entities, and internal parameter entities, but they
are not XML MIME entities. are not XML MIME entities.
Application/xml and application/xml-external-parsed-entity are Compared to [RFC2376] or [RFC3023], this specification alters the
recommended. Compared to [RFC2376] or [RFC3023], this specification charset handling of text/xml and text/xml-external-parsed-entity,
alters the charset handling of text/xml and text/xml-external-parsed- treating them no differently from the respective application/ types,
entity, treating them no differently from the respective application/ however application/xml and application/xml-external-parsed-entity
types. The reasons are as follows: are still RECOMMENDED, to avoid possible confusion based on the
earlier distinction. The former confusion around the question of
Conflicting specifications regarding the character encoding have default character sets for the text/xml... types has been resolved by
caused confusion. On the one hand, [RFC2046] specifies "The [HTTPbis] changing [RFC2616] by removing the ISO-8859-1 default and
default character set, which must be assumed in the absence of a not defining any default at all, as well as [RFC6657] updating
charset parameter, is US-ASCII.", [RFC2616] Section 3.7.1, defines [RFC2046] to remove the US-ASCII default. See Section 3.6 for the
that "media subtypes of the 'text' type are defined to have a now-unified approach to the charset parameter which results.
default charset value of 'ISO-8859-1'", and [RFC2376] as well as
[RFC3023] specify the default charset is US-ASCII.
On the other hand, implementors and users of XML parsers,
following Appendix F of [XML], assume that the default is provided
by the XML encoding declaration or BOM. Note that this conflict
did not exist for application/xml or application/xml-external-
parsed-entity (see "Optional parameters" of application/xml
registration in Section 3.1).
The current situation, reflected in this specification, has been
simplified by [RFC6657] updating [RFC2046] to remove the US-ASCII
default. Furthermore, in accordance with [RFC6657]'s other
recommendations, [HTTPbis] changes [RFC2616] by removing the
ISO-8859-1 default and not defining any default at all.
The top-level media type "text" has some restrictions on MIME
entities and they are described in [RFC2045] and [RFC2046]. In
particular, for transports other than HTTP [RFC2616] or HTTPS
(which uses a MIME-like mechanism). the UTF-16 family, UCS-4, and
UTF-32 are not allowed However, section 4.3.3 of [XML] says:
"Each external parsed entity in an XML document may use a
different encoding for its characters. All XML processors MUST
be able to read entities in both the UTF-8 and UTF-16
encodings."
Thus, although all XML processors can read entities in at least
UTF-16, if an XML document or external parsed entity is encoded in
such character encoding schemes, it could not be labeled as text/
xml or text/xml-external-parsed-entity (except for HTTP).
It is not possible to deprecate text/xml because it is widely used
in practice, and implementations are largely interoperable,
following the rules of Appendix F of [XML] and ignoring the
requirements of [RFC3023].
XML provides a general framework for defining sequences of structured XML provides a general framework for defining sequences of structured
data. In some cases, it may be desirable to define new media types data. It is often appropriate to define new media types that use XML
that use XML but define a specific application of XML, perhaps due to but define a specific application of XML, due to domain-specific
domain-specific display, editing, security considerations or runtime display, editing, security considerations or runtime information.
information. Furthermore, such media types may allow UTF-8 or UTF-16 Furthermore, such media types may allow UTF-8 or UTF-16 only and
only and prohibit other charsets. This specification does not prohibit other character sets. This specification does not prohibit
prohibit such media types and in fact expects them to proliferate. such media types and in fact expects them to proliferate. However,
However, developers of such media types are STRONGLY RECOMMENDED to developers of such media types are RECOMMENDED to use this
use this specification as a basis for their registration. In specification as a basis for their registration. See Section 8 for
particular, the charset parameter, if used, MUST agree with the in- more detailed recommendations on using the '+xml' suffix for
band XML encoding of the XML entity, as described in Section 3.6, in registration of such media types.
order to enhance interoperability.
An XML document labeled as application/xml or text/xml, or with a An XML document labeled as application/xml or text/xml, or with a
'+xml' media type, might contain namespace declarations, stylesheet- '+xml' media type, might contain namespace declarations, stylesheet-
linking processing instructions (PIs), schema information, or other linking processing instructions (PIs), schema information, or other
declarations that might be used to suggest how the document is to be declarations that might be used to suggest how the document is to be
processed. For example, a document might have the XHTML namespace processed. For example, a document might have the XHTML namespace
and a reference to a CSS stylesheet. Such a document might be and a reference to a CSS stylesheet. Such a document might be
handled by applications that would use this information to dispatch handled by applications that would use this information to dispatch
the document for appropriate processing. the document for appropriate processing.
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Type name: application Type name: application
Subtype name: xml Subtype name: xml
Required parameters: none Required parameters: none
Optional parameters: charset Optional parameters: charset
See Section 3.6. See Section 3.6.
Encoding considerations: This media type MAY be encoded as Encoding considerations: Depending on the charset encoding used, XML
appropriate for the charset and the capabilities of the underlying MIME entities may consist of 7bit, 8bit or binary data [RFC6838].
MIME transport. For 7-bit transports, data in either UTF-8 or For 7-bit transports, 7bit data, for example data with charset
UTF-16 MUST be encoded in quoted-printable or base64. For 8-bit encoding US-ASCII, does not require content-transfer-encoding, but
clean transport (e.g., 8BITMIME [RFC6152] ESMTP or NNTP 8bit or binary data, for example data with charset encoding UTF-8
[RFC3977]), UTF-8 is not encoded, but the UTF-16 family MUST be or UTF-16, MUST be content-transfer-encoded in quoted-printable or
encoded in base64. For binary clean transports (e.g., HTTP base64. For 8-bit clean transport (e.g. 8BITMIME [RFC6152],
[RFC2616]), no content-transfer-encoding is necessary. ESMTP or NNTP [RFC3977]), 7bit or 8bit data, for example data with
charset encoding UTF-8 or US-ASCII, does not require content-
transfer-encoding, but binary data, for example data with a
charset encoding from the UTF-16 family, MUST be content-transfer-
encoded in base64. For binary clean transports (e.g. HTTP
[RFC2616]), no content-transfer-encoding is necessary (or even
possible, in the case of HTTP) for 7bit, 8bit or binary data.
Security considerations: See Section 11. Security considerations: See Section 11.
Interoperability considerations: XML has proven to be interoperable Interoperability considerations: XML has proven to be interoperable
across both generic and task-specific applications and for import across both generic and task-specific applications and for import
and export from multiple XML authoring and editting tools. For and export from multiple XML authoring and editing tools. For
maximum interoperability, validating processors are recommended. maximum interoperability, validating processors are recommended.
Although non-validating processors may be more efficient, they are Although non-validating processors may be more efficient, they are
not required to handle all features of XML. For further not required to handle all features of XML. For further
information, see sub-section 2.9 "Standalone Document Declaration" information, see sub-section 2.9 "Standalone Document Declaration"
and section 5 "Conformance" of [XML] . and section 5 "Conformance" of [XML] .
Published specification: Extensible Markup Language (XML) 1.0 (Fifth Published specification: Extensible Markup Language (XML) 1.0 (Fifth
Edition) [XML], Extensible Markup Language (XML) 1.1 (Second Edition) [XML] or subsequent editions or versions thereof.
Edition) [XML1.1].
Applications that use this media type: XML is device-, platform-, Applications that use this media type: XML is device-, platform-,
and vendor-neutral and is supported by a wide range of generic XML and vendor-neutral and is supported by a wide range of generic XML
tools (editors, parsers, Web agents, ...) and task-specific tools (editors, parsers, Web agents, ...), generic and task-
applications. specific applications.
Additional information: Additional information:
Magic number(s): None. Magic number(s): None.
Although no byte sequences can be counted on to always be Although no byte sequences can be counted on to always be
present, XML MIME entities in ASCII-compatible charsets present, XML MIME entities in ASCII-compatible character sets
(including UTF-8) often begin with hexadecimal 3C 3F 78 6D 6C (including UTF-8) often begin with hexadecimal 3C 3F 78 6D 6C
("<?xml"), and those in UTF-16 often begin with hexadecimal FE ("<?xml"), and those in UTF-16 often begin with hexadecimal FE
FF 00 3C 00 3F 00 78 00 6D 00 6C or FF FE 3C 00 3F 00 78 00 6D FF 00 3C 00 3F 00 78 00 6D 00 6C or FF FE 3C 00 3F 00 78 00 6D
00 6C 00 (the Byte Order Mark (BOM) followed by "<?xml"). For 00 6C 00 (the Byte Order Mark (BOM) followed by "<?xml"). For
more information, see Appendix F of [XML]. more information, see Appendix F of [XML].
File extension(s): .xml File extension(s): .xml
Macintosh File Type Code(s): "TEXT" Macintosh File Type Code(s): "TEXT"
Base URI: See Section 6
Person and email address for further information: See Authors' Person and email address for further information: See Authors'
Addresses section Addresses section
Intended usage: COMMON Intended usage: COMMON
Author: See Authors' Addresses section Author: See Authors' Addresses section
Change controller: The XML specification is a work product of the Change controller: The XML specification is a work product of the
World Wide Web Consortium's XML Working Group World Wide Web Consortium's XML Working Group
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Additional information: Additional information:
Magic number(s): Same as application/xml as described in Magic number(s): Same as application/xml as described in
Section 3.1. Section 3.1.
File extension(s): .xml or .ent File extension(s): .xml or .ent
Macintosh File Type Code(s): "TEXT" Macintosh File Type Code(s): "TEXT"
Base URI: See Section 6
Person and email address for further information: See Authors' Person and email address for further information: See Authors'
Addresses section. Addresses section.
Intended usage: COMMON Intended usage: COMMON
Author: See Authors' Addresses section. Author: See Authors' Addresses section.
Change controller: The XML specification is a work product of the Change controller: The XML specification is a work product of the
World Wide Web Consortium's XML Working Group World Wide Web Consortium's XML Working Group
skipping to change at page 9, line 44 skipping to change at page 9, line 4
3.5. Application/xml-dtd Registration 3.5. Application/xml-dtd Registration
Type name: application Type name: application
Subtype name: xml-dtd Subtype name: xml-dtd
Required parameters: none Required parameters: none
Optional parameters: charset Optional parameters: charset
See Section 3.6. See Section 3.6.
Encoding considerations: Same as Section 3.1. Encoding considerations: Same as Section 3.1.
Security considerations: See Section 11. Security considerations: See Section 11.
Interoperability considerations: XML DTDs have proven to be Interoperability considerations: XML DTDs have proven to be
interoperable by DTD authoring tools and XML browsers, among interoperable by DTD authoring tools and XML validators, among
others. others.
Published specification: Same as application/xml as described in Published specification: Same as application/xml as described in
Section 3.1. Section 3.1.
Applications which use this media type: DTD authoring tools handle Applications which use this media type: DTD authoring tools handle
external DTD subsets as well as external parameter entities. XML external DTD subsets as well as external parameter entities. XML
browsers may also access external DTD subsets and external validators may also access external DTD subsets and external
parameter entities. parameter entities.
Additional information: Additional information:
Magic number(s): Same as application/xml as described in Magic number(s): Same as application/xml as described in
Section 3.1. Section 3.1.
File extension(s): .dtd or .mod File extension(s): .dtd or .mod
Macintosh File Type Code(s): "TEXT" Macintosh File Type Code(s): "TEXT"
skipping to change at page 10, line 38 skipping to change at page 9, line 43
Intended usage: COMMON Intended usage: COMMON
Author: See Authors' Addresses section. Author: See Authors' Addresses section.
Change controller: The XML specification is a work product of the Change controller: The XML specification is a work product of the
World Wide Web Consortium's XML Working Group World Wide Web Consortium's XML Working Group
3.6. Charset considerations 3.6. Charset considerations
The charset parameter MUST only be used, when the charset is reliably When a charset parameter is specified for an XML MIME entity which
known and agrees with the in-band XML encoding declaration. This contains in-band encoding information, that is, either a BOM
information can be used by non-XML processors to determine (Section 4) or an XML encoding declaration or both, the normative
authoritatively the charset of the XML MIME entity. The charset component of the [XML] specification leaves the question open as to
parameter can also be used to provide protocol-specific operations, which should be taken to be authoritative in the case of conflict.
such as charset-based content negotiation in HTTP. In its (non-normative) Appendix F it defers to this specification:
[T]he preferred method of handling conflict should be specified as
part of the higher-level protocol used to deliver XML. In
particular, please refer to [IETF RFC 3023] or its successor
All processors SHOULD treat a BOM (Section 4) as authoritative if it
is present in an XML MIME entity. In the absence of a BOM
(Section 4), all processors SHOULD treat the charset parameter as
authoritative. Section 4.3.3 of the [XML] specification does _not_
make it an error for the charset parameter and the XML encoding
declaration to be inconsistent.
XML-aware processors SHOULD supply a charset parameter and/or an
appropriate BOM with non-UTF-8-encoded XML MIME entities which lack
an encoding declaration, or whose encoding declaration is known to be
incorrect (for example, as a result of transcoding).
The charset parameter MUST NOT be used unless the charset is reliably
known. This information will be used by all processors to determine
authoritatively the charset of the XML MIME entity in the absence of
a BOM.
"utf-8" [RFC3629] and "utf-16" [RFC2781] are the recommended values, "utf-8" [RFC3629] and "utf-16" [RFC2781] are the recommended values,
representing the UTF-8 and UTF-16 charsets, respectively. These representing the UTF-8 and UTF-16 character sets, respectively.
charsets are preferred since they are supported by all conforming These character sets are preferred since they are supported by all
processors of [XML]. conforming processors of [XML].
If an entity of one of the types defined above is received where the If an entity of one of the types defined above is received where the
charset parameter is omitted, no information is being provided about charset parameter is omitted, no information is being provided about
the charset by the MIME Content-Type header. Conforming XML the charset by the MIME Content-Type header. Conforming XML
processors MUST follow the requirements in section 4.3.3 of [XML] processors MUST follow the requirements in section 4.3.3 of [XML]
that directly address this contingency. However, MIME processors that directly address this contingency. MIME processors that are not
that are not XML processors SHOULD NOT assume a default charset if XML processors SHOULD NOT assume a default charset if the charset
the charset parameter is omitted from such an entity. parameter is omitted from such an entity.
Since a receiving application can, with very high reliability,
determine the encoding of an XML document by reading it, the in-band
XML encoding declaration SHOULD be provided.
3.6.1. Background
There are several reasons that the charset parameter is optionally
allowed. First, recent web servers have been improved so that users
can specify the charset parameter. Second, [RFC2130] (informative)
specifies that the recommended specification scheme is the "charset"
parameter.
On the other hand, it has been argued that the charset parameter
should be omitted and the mechanism described in Appendix F of [XML]
(which is non-normative) should be solely relied on. This approach
would allow users to avoid configuration of the charset parameter; an
XML document stored in a file is likely to contain a correct encoding
declaration or BOM (if necessary), since the operating system does
not typically provide charset information for files. If users would
like to rely on the in-band XML encoding declaration or BOM and/or to
conceal charset information from non-XML processors, they can omit
the parameter.
4. The Byte Order Mark (BOM) and Conversions to/from the UTF-16 Charset 4. The Byte Order Mark (BOM) and Charset Conversions
Section 4.3.3 of [XML] specifies that XML MIME entities in the Section 4.3.3 of [XML] specifies that XML MIME entities in the
charset "utf-16" MUST begin with a byte order mark (BOM), which is a charset "utf-16" MUST begin with a byte order mark (BOM), which is a
hexadecimal octet sequence 0xFE 0xFF (or 0xFF 0xFE, depending on hexadecimal octet sequence 0xFE 0xFF (or 0xFF 0xFE, depending on
endian). The XML Recommendation further states that the BOM is an endian). The XML Recommendation further states that the BOM is an
encoding signature, and is not part of either the markup or the encoding signature, and is not part of either the markup or the
character data of the XML document. character data of the XML document.
Due to the presence of the BOM, applications that convert XML from Due to the presence of the BOM, applications that convert XML from
"utf-16" to a non-Unicode encoding MUST strip the BOM before "utf-16" to an encoding other than "utf-8" MUST strip the BOM before
conversion. Similarly, when converting from another encoding into conversion. Similarly, when converting from another encoding into
"utf-16", the BOM MUST be added after conversion is complete. "utf-16", the BOM MUST be added after conversion is complete unless
the original encoding was "utf-8" and a BOM was already present, in
which case it will have been transcoded into a "utf-16" BOM already.
Section 4.3.3 of [XML] also allows for XML MIME entities in the
charset "utf-8" to begin with a byte order mark (BOM), which is a
hexadecimal octet sequence 0xEF 0xBB 0xBF, also defined to be an
encoding signature, and not part of either the markup or the
character data of the XML document.
Applications that convert XML from "utf-8" to an encoding other than
"utf-16" MUST strip the BOM, if present, before conversion.
Applications which convert XML into "utf-8" SHOULD add a BOM after
conversion is complete.
In addition to the charset "utf-16", [RFC2781] introduces "utf-16le" In addition to the charset "utf-16", [RFC2781] introduces "utf-16le"
(little endian) and "utf-16be" (big endian) as well. The BOM is (little endian) and "utf-16be" (big endian) as well. The BOM is
prohibited for these charsets. When an XML MIME entity is encoded in prohibited for these character sets. When an XML MIME entity is
"utf-16le" or "utf-16be", it MUST NOT begin with the BOM but SHOULD encoded in "utf-16le" or "utf-16be", it MUST NOT begin with the BOM
contain an in-band XML encoding declaration. Conversion from but SHOULD contain an in-band XML encoding declaration. Conversion
"utf-16" to "utf-16be" or "utf-16le" and conversion in the other from "utf-16"or "utf-8" to "utf-16be" or "utf-16le" and conversion in
direction MUST strip or add the BOM, respectively. the other direction MUST strip or add the appropriate BOM,
respectively.
5. Fragment Identifiers 5. Fragment Identifiers
Uniform Resource Identifiers (URIs) may contain fragment identifiers Uniform Resource Identifiers (URIs) can contain fragment identifiers
(see Section 3.5 of [RFC3986]). Likewise, Internationalized Resource (see Section 3.5 of [RFC3986]).Specifying the syntax and semantics of
Identifiers (IRIs) [RFC3987] may contain fragment identifiers. fragment identifiers is devolved by [RFC3986] to the appropriate
media type registration.
The syntax and semantics of fragment identifiers for the XML media The syntax and semantics of fragment identifiers for the XML media
types defined in this specification are based on the types defined in this specification are based on the
[XPointerFramework] W3C Recommendation. It allows simple names, and [XPointerFramework] W3C Recommendation. It allows simple names, and
more complex constructions based on named schemes. When the syntax more complex constructions based on named schemes. When the syntax
of a fragment identifier part of any URI or IRI with a retrieved of a fragment identifier part of any URI or IRI with a retrieved
media type governed by this specification conforms to the syntax media type governed by this specification conforms to the syntax
specified in [XPointerFramework], conformant applications MUST specified in [XPointerFramework], conforming applications MUST
interpret such fragment identifiers as designating that part of the interpret such fragment identifiers as designating that part of the
retrieved representation specified by [XPointerFramework] and retrieved representation specified by [XPointerFramework] and
whatever other specifications define any XPointer schemes used. whatever other specifications define any XPointer schemes used.
Conformant applications MUST support the 'element' scheme as defined Conforming applications MUST support the 'element' scheme as defined
in [XPointerElement], but need not support other schemes. in [XPointerElement], but need not support other schemes.
If an XPointer error is reported in the attempt to process the part, If an XPointer error is reported in the attempt to process the part,
this specification does not define an interpretation for the part. this specification does not define an interpretation for the part.
A registry of XPointer schemes [XPtrReg] is maintained at the W3C. A registry of XPointer schemes [XPtrReg] is maintained at the W3C.
Document authors SHOULD NOT use unregistered schemes. Scheme authors Document authors SHOULD NOT use unregistered schemes. Scheme authors
SHOULD register their schemes. SHOULD register their schemes ([XPtrRegPolicy] describes requirements
and procedures for doing so).
See Section 8.1 for additional rquirements which apply when an XML- See Section 8.1 for additional requirements which apply when an XML-
based MIME media type follows the naming convention '+xml'. based media type follows the naming convention '+xml'.
If [XPointerFramework] and [XPointerElement] are inappropriate for If [XPointerFramework] and [XPointerElement] are inappropriate for
some XML-based media type, it SHOULD NOT follow the naming convention some XML-based media type, it SHOULD NOT follow the naming convention
'+xml'. '+xml'.
When a URI has a fragment identifier, it is encoded by a limited When a URI has a fragment identifier, it is encoded by a limited
subset of the repertoire of US-ASCII [ASCII] characters, as defined subset of the repertoire of US-ASCII [ASCII] characters, as defined
in [RFC3986]. When an IRI contains a fragment identifier, it is in [RFC3986].
encoded by a much wider repertoire of characters. The conversion
between IRI fragment identifiers and URI fragment identifiers is
presented in Section 7 of [RFC3987].
6. The Base URI 6. The Base URI
Section 5.1 of [RFC3986] specifies that the semantics of a relative Section 5.1 of [RFC3986] specifies that the semantics of a relative
URI reference embedded in a MIME entity is dependent on the base URI. URI reference embedded in a MIME entity is dependent on the base URI.
The base URI is either (1) the base URI embedded in context, (2) the The base URI is established by (1) the base URI embedded in content,
base URI from the encapsulating entity, (3) the base URI from the (2) the base URI from the encapsulating entity, (3) the base URI from
Retrieval URI, or (4) the default base URI, where (1) has the highest the Retrieval URI, or (4) the default base URI, in order of
precedence. [RFC3986] further specifies that the mechanism for precedence. [RFC3986] further specifies that the mechanism for
embedding the base URI is dependent on the media type. embedding the base URI is dependent on the media type.
The media type dependent mechanism for embedding the base URI in a This specification accordingly provides the following media type
MIME entity of type application/xml, text/xml, application/xml- dependent mechanism for embedding the base URI in a MIME entity of
external-parsed-entity or text/xml-external-parsed-entity is to use type application/xml, text/xml, application/xml-external-parsed-
the xml:base attribute described in detail in [XBase]. entity or text/xml-external-parsed-entity: An XML MIME entity MAY use
the xml:base attribute, as described in detail in [XMLBase], to
establish a base URI for that entity.
Note that the base URI may be embedded in a different MIME entity, Note that the base URI itself might be embedded in a different MIME
since the default value for the xml:base attribute may be specified entity, since the default value for the xml:base attribute can be
in an external DTD subset or external parameter entity. specified in an external DTD subset or external parameter entity.
Since conforming XML processors need not always read and process
external entities, the effect of such an external default is
uncertain and therefore its use is NOT RECOMMENDED.
7. XML Versions 7. XML Versions
application/xml, application/xml-external-parsed-entity, and application/xml, application/xml-external-parsed-entity, and
application/xml-dtd, text/xml and text/xml-external-parsed-entity are application/xml-dtd, text/xml and text/xml-external-parsed-entity are
to be used with [XML] In all examples herein where version="1.0" is to be used with [XML]. In all examples herein where version="1.0" is
shown, it is understood that version="1.1" may also be used, shown, it is understood that version="1.1" may also be used,
providing the content does indeed conform to [XML1.1]. providing the content does indeed conform to [XML1.1].
The normative requirement of this specification upon XML is to follow The normative requirement of this specification upon XML documents
the requirements of [XML], section 4.3.3. Except for minor and processors is to follow the requirements of [XML], section 4.3.3.
clarifications, that section is substantially identical from the Except for minor clarifications, that section is substantially
first edition to the current (5th) edition of XML 1.0, and for XML identical from the first edition to the current (5th) edition of XML
1.1. Therefore, this specification may be used with any version or 1.0, and for XML 1.1 1st or 2nd edition [XML1.1]. Therefore,
edition of XML 1.0 or 1.1. references herein to [XML] may be interpreted as referencing any
existing version or edition of XML, or any subsequent edition or
version which makes no incompatible changes to that section.
Specifications and recommendations based on or referring to this RFC Specifications and recommendations based on or referring to this RFC
SHOULD indicate any limitations on the particular versions of XML to SHOULD indicate any limitations on the particular versions or
be used. For example, a particular specification might indicate: editions of XML to be used.
"content MUST be represented using media-type application/xml, and
the document must either (a) carry an xml declaration specifying
version="1.0" or (b) omit the XML declaration, in which case per the
XML recommendation the version defaults to 1.0"
8. A Naming Convention for XML-Based Media Types 8. A Naming Convention for XML-Based Media Types
This section supersedes the earlier registration of the '+xml' suffix This section supersedes the earlier registration of the '+xml' suffix
[RFC6839]. [RFC6839].
This specification recommends the use of a naming convention (a This specification recommends the use of a naming convention (a
suffix of '+xml') for identifying XML-based MIME media types, suffix of '+xml') for identifying XML-based media types, in line with
whatever their particular content may represent, in line with the the recognition in [RFC6838] of structured syntax name suffixes.
recognition in [RFC6838] of structured syntax name suffixes. This This allows the use of generic XML processors and technologies on a
allows the use of generic XML processors and technologies on a wide wide variety of different XML document types at a minimum cost, using
variety of different XML document types at a minimum cost, using
existing frameworks for media type registration. existing frameworks for media type registration.
When a new media type is introduced for an XML-based format, the name When a new media type is introduced for an XML-based format, the name
of the media type SHOULD end with '+xml'. This convention will allow of the media type SHOULD end with '+xml' unless generic XML
applications that can process XML generically to detect that the MIME processing is in some way inappropriate for documents of the new
entity is supposed to be an XML document, verify this assumption by type. This convention will allow applications that can process XML
invoking some XML processor, and then process the XML document generically to detect that the MIME entity is supposed to be an XML
accordingly. Applications may match for types that represent XML document, verify this assumption by invoking some XML processor, and
MIME entities by comparing the subtype to the pattern '*/*+xml'. (Of then process the XML document accordingly. Applications may match
course, 4 of the 5 media types defined in this specification -- text/ for types that represent XML MIME entities by comparing the subtype
xml, application/xml, text/xml-external-parsed-entity, and to the pattern '*/*+xml'. (However note that 4 of the 5 media types
application/xml-external-parsed-entity -- also represent XML MIME defined in this specification -- text/xml, application/xml, text/xml-
entities while not conforming to the '*/*+xml' pattern.) external-parsed-entity, and application/xml-external-parsed-entity --
also represent XML MIME entities while not conforming to the '*/
NOTE: Section 14.1 of HTTP [RFC2616] does not support Accept *+xml' pattern.)
NOTE: Section 5.3.2HTTPbis [HTTPbis] does not support Accept
headers of the form "Accept: */*+xml" and so this header MUST NOT headers of the form "Accept: */*+xml" and so this header MUST NOT
be used in this way. Instead, content negotiation [RFC2703] could be used in this way.
potentially be used if an XML-based MIME type were needed.
Media types following the naming convention '+xml' SHOULD introduce Media types following the naming convention '+xml' SHOULD introduce
the charset parameter for consistency, since XML-generic processing the charset parameter for consistency, since XML-generic processing
applies the same program for any such media type. However, there are applies the same program for any such media type. However, there are
some cases that the charset parameter need not be introduced. For some cases that the charset parameter need not be introduced. For
example: example:
When an XML-based media type is restricted to UTF-8, it is not When an XML-based media type is restricted to UTF-8, it is not
necessary to introduce the charset parameter. "UTF-8 only" is a necessary to introduce the charset parameter. "UTF-8 only" is a
generic principle and UTF-8 is the default of XML. generic principle and UTF-8 is the default of XML.
skipping to change at page 14, line 51 skipping to change at page 14, line 29
might not be unreasonable to omit the charset parameter. Neither might not be unreasonable to omit the charset parameter. Neither
UTF-8 nor UTF-16 require in-band XML encoding declarations. UTF-8 nor UTF-16 require in-band XML encoding declarations.
XML generic processing is not always appropriate for XML-based media XML generic processing is not always appropriate for XML-based media
types. For example, authors of some such media types may wish that types. For example, authors of some such media types may wish that
the types remain entirely opaque except to applications that are the types remain entirely opaque except to applications that are
specifically designed to deal with that media type. By NOT following specifically designed to deal with that media type. By NOT following
the naming convention '+xml', such media types can avoid XML-generic the naming convention '+xml', such media types can avoid XML-generic
processing. Since generic processing will be useful in many cases, processing. Since generic processing will be useful in many cases,
however -- including in some situations that are difficult to predict however -- including in some situations that are difficult to predict
ahead of time -- those registering media types SHOULD use the '+xml' ahead of time -- the '+xml' convention is to be preferred unless
convention unless they have a particularly compelling reason not to. there is some particularly compelling reason not to.
The registration process for specific '+xml' media types is described The registration process for specific '+xml' media types is described
in [RFC6838] and [RFC6839]. The registrar for the IETF tree will in [RFC6838]. The registrar for the IETF tree will encourage new
encourage new XML-based media type registrations in the IETF tree to XML-based media type registrations in the IETF tree to follow this
follow this guideline. Registrars for other trees SHOULD follow this guideline. Registrars for other trees SHOULD follow this convention
convention in order to ensure maximum interoperability of their XML- in order to ensure maximum interoperability of their XML-based
based documents. Similarly, media subtypes that do not represent XML documents. Similarly, media subtypes that do not represent XML MIME
MIME entities MUST NOT be allowed to register with a '+xml' suffix. entities MUST NOT be allowed to register with a '+xml' suffix.
8.1. Referencing 8.1. Referencing
Registrations for new XML-based media types under top-level types Registrations for new XML-based media types under top-level types
SHOULD, in specifying the charset parameter and encoding SHOULD, in specifying the charset parameter and encoding
considerations, define them as: "Same as [charset parameter / considerations, define them as: "Same as [charset parameter /
encoding considerations] of application/xml as specified in RFC encoding considerations] of application/xml as specified in RFC
XXXX." XXXX."
The use of the charset parameter is STRONGLY RECOMMENDED, since this Enabling the charset parameter is RECOMMENDED, since this information
information can be used by XML processors to determine can be used by XML processors to determine authoritatively the
authoritatively the charset of the XML MIME entity. If there are charset of the XML MIME entity in the absence of a BOM. If there are
some reasons not to follow this advice, they SHOULD be included as some reasons not to follow this advice, they SHOULD be included as
part of the registration. As shown above, two such reasons are part of the registration. As shown above, two such reasons are
"UTF-8 only" or "UTF-8 or UTF-16 only". "UTF-8 only" or "UTF-8 or UTF-16 only".
These registrations SHOULD specify that the XML-based media type These registrations SHOULD specify that the XML-based media type
being registered has all of the security considerations described in being registered has all of the security considerations described in
RFC XXXX plus any additional considerations specific to that media RFC XXXX plus any additional considerations specific to that media
type. type.
These registrations SHOULD also make reference to RFC XXXX in These registrations SHOULD also make reference to RFC XXXX in
skipping to change at page 16, line 19 skipping to change at page 15, line 47
(which MUST NOT overlap with [XPointerFramework] syntax) together (which MUST NOT overlap with [XPointerFramework] syntax) together
with associated semantics, and MAY add additional semantics for with associated semantics, and MAY add additional semantics for
barename XPointers which, as provided for in Section 5, will only barename XPointers which, as provided for in Section 5, will only
apply when this specification does not define an interpretation. apply when this specification does not define an interpretation.
In practice these constraints imply that for a fragment In practice these constraints imply that for a fragment
identifier addressed to an instance of a specific "xxx/yyy+xml" identifier addressed to an instance of a specific "xxx/yyy+xml"
type, there are three cases: type, there are three cases:
For fragment identifiers matching the syntax defined in For fragment identifiers matching the syntax defined in
Section 5, where the fragment identifier resolves per the [XPointerFramework], where the fragment identifier resolves
rules specified there, then process as specified there; per the rules specified there, then process as specified
there;
For fragment identifiers matching the syntax defined in For fragment identifiers matching the syntax defined in
Section 5, where the fragment identifier does _not_ resolve [XPointerFramework], where the fragment identifier does
per the rules specified there, then process as specified in _not_ resolve per the rules specified there, then process as
"xxx/yyy+xml"; specified in "xxx/yyy+xml";
For fragment identifiers _not_ matching the syntax defined For fragment identifiers _not_ matching the syntax defined
in Section 5, then process as specified in "xxx/yyy+xml". in [XPointerFramework], then process as specified in "xxx/
yyy+xml".A fragment identifier of the form
"xywh=160,120,320,240", as defined in [MediaFrags], which
might be used in a URI for an XML-encoded image, would fall
in this category.
Interoperability considerations: Same as Section 3.1. See above, Interoperability considerations: Same as Section 3.1. See above,
and also Section 3.6, for guidelines on the use of the 'charset' and also Section 3.6, for guidelines on the use of the 'charset'
parameter. parameter.
Security considerations: See Section 11. Security considerations: See Section 11.
Contact: See Authors' Addresses section. Contact: See Authors' Addresses section.
Author: See Authors' Addresses section. Author: See Authors' Addresses section.
Change controller: The XML specification is a work product of the Change controller: The XML specification is a work product of the
World Wide Web Consortium's XML Working Group. World Wide Web Consortium's XML Working Group.
9. Examples 9. Examples
The examples below give the charset portion, if any, of the value of The examples below give the charset portion, if any, of the value of
the MIME Content-type header and the XML declaration or Text the MIME Content-type header and the XML declaration or Text
declaration (which includes the encoding declaration) inside the XML declaration (which includes the encoding declaration) inside the XML
MIME entity. For UTF-16 examples, the Byte Order Mark character is MIME entity. For UTF-16 examples, the Byte Order Mark character
denoted as "{BOM}", and the XML or Text declaration is assumed to appropriately UTF-16-encoded is denoted as "{BOM}", and the XML or
come at the beginning of the XML MIME entity, immediately following Text declaration is assumed to come at the beginning of the XML MIME
the BOM. Note that other MIME headers may be present, and the XML entity, immediately following the encoded BOM. Note that other MIME
MIME entity may contain other data in addition to the XML headers may be present, and the XML MIME entity may contain other
declaration; the examples focus on the Content-type header and the data in addition to the XML declaration; the examples focus on the
encoding declaration for clarity. Content-type header and the encoding declaration for clarity.
All the examples below apply to all five media types declared above All the examples below apply to all five media types declared above
in Section 3, as well as to any media types declared using the '+xml' in Section 3, as well as to any media types declared using the '+xml'
convention. See the XML MIME entities table (Section 3, Paragraph 2) convention (with the exception of the examples involving the charset
for discussion of which types are appropriate for which varieties of parameter for any such media types which to not enable its use). See
XML MIME entities. the XML MIME entities table (Section 3, Paragraph 2) for discussion
of which types are appropriate for which varieties of XML MIME
entities.
This section is non-normative. In particular, note that all "MUST" This section is non-normative. In particular, note that all
language herein reproduces or summarizes the consequences of [RFC2119] language herein reproduces or summarizes the consequences
normative statement already made above, and have no independent of normative statements already made above, and has no independent
normative force. normative force, and accordingly does not appear in uppercase.
9.1. UTF-8 Charset 9.1. UTF-8 Charset
Content-type charset: charset="utf-8" Content-type charset: charset="utf-8"
<?xml version="1.0" encoding="utf-8"?> <?xml version="1.0" encoding="utf-8"?>
This is the recommended encoding for use with all the media types This is the recommended encoding for use with all the media types
defined in this specification. Since the charset parameter is defined in this specification. Since the charset parameter is
provided, both MIME and XML processors MUST treat the enclosed entity provided and there is no BOM, both MIME and XML processors must treat
as UTF-8 encoded. the enclosed entity as UTF-8 encoded.
If sent using a 7-bit transport (e.g. SMTP [RFC5321]), the XML MIME If sent using a 7-bit transport (e.g. SMTP [RFC5321]), the XML MIME
entity MUST use a content-transfer-encoding of either quoted- entity must use a content-transfer-encoding of either quoted-
printable or base64. For an 8-bit clean transport (e.g., 8BITMIME printable or base64. For an 8-bit clean transport (e.g. 8BITMIME,
ESMTP or NNTP), or a binary clean transport (e.g., HTTP), no content- ESMTP or NNTP), or a binary clean transport (e.g. HTTP), no content-
transfer-encoding is necessary. transfer-encoding is necessary (or even possible, in the case of
HTTP).
9.2. UTF-16 Charset 9.2. UTF-16 Charset
Content-type charset: charset="utf-16" Content-type charset: charset="utf-16"
{BOM}<?xml version="1.0" encoding="utf-16"?> {BOM}<?xml version="1.0" encoding="utf-16"?>
or or
{BOM}<?xml version="1.0"?> {BOM}<?xml version="1.0"?>
For application... cases, if sent using a 7-bit transport (e.g.,
SMTP) or an 8-bit clean transport (e.g., 8BITMIME ESMTP or NNTP), the
XML MIME entity MUST be encoded in quoted-printable or base64; for a
binary clean transport (e.g., HTTP), no content-transfer-encoding is
necessary.
As described in [RFC2781], the UTF-16 family MUST NOT be used with For application/... cases, if sent using a 7-bit transport (e.g.
SMTP) or an 8-bit clean transport (e.g. 8BITMIME, ESMTP or NNTP),
the XML MIME entity must be encoded in quoted-printable or base64;
for a binary clean transport (e.g. HTTP), no content-transfer-
encoding is necessary (or even possible, in the case of HTTP).
As described in [RFC2781], the UTF-16 family must not be used with
media types under the top-level type "text" except over HTTP or HTTPS media types under the top-level type "text" except over HTTP or HTTPS
(see section 19.4.1 of [RFC2616] for details). Hence this example is (see section 19.4.2 of [RFC2616] for details). Hence this example is
only possible in text/... cases when the XML MIME entity is only possible in text/... cases when the XML MIME entity is
transmitted via HTTP or HTTPS, which use a MIME-like mechanism and transmitted via HTTP or HTTPS, which use a MIME-like mechanism and
are binary-clean protocols, hence do not perform CR and LF are binary-clean protocols, hence do not perform CR and LF
transformations and allow NUL octets. Since HTTP is binary clean, no transformations and allow NUL octets. Since HTTP is binary clean, no
content-transfer-encoding is necessary. content-transfer-encoding is necessary (or even possible).
9.3. Omitted Charset and 8-bit MIME entity 9.3. Omitted Charset and 8-bit MIME entity
Content-type charset: [none] Content-type charset: [none]
<?xml version="1.0" encoding="iso-8859-1"?> <?xml version="1.0" encoding="iso-8859-1"?>
Since the charset parameter is not provided in the Content-Type Since the charset parameter is not provided in the Content-Type
header, XML processors MUST treat the "iso-8859-1" encoding as header and there is no BOM, XML processors must treat the
authoritative. XML-unaware MIME processors SHOULD make no "iso-8859-1" encoding as authoritative. XML-unaware MIME processors
assumptions about the charset of the XML MIME entity. should make no assumptions about the charset of the XML MIME entity.
9.4. Omitted Charset and 16-bit MIME entity 9.4. Omitted Charset and 16-bit MIME entity
Content-type charset: [none] Content-type charset: [none]
{BOM}<?xml version="1.0" encoding="utf-16"?> {BOM}<?xml version="1.0" encoding="utf-16"?>
or or
{BOM}<?xml version="1.0"?> {BOM}<?xml version="1.0"?>
This example shows a 16-bit MIME entity with no charset parameter. This example shows a 16-bit MIME entity with no charset parameter.
Since the charset parameter is not provided in the Content-Type However since there is a BOM all processors must treat the entity as
header, in this case XML processors MUST treat the "utf-16" encoding UTF-16-encoded.
and/or the BOM as authoritative. XML-unaware MIME processors SHOULD
make no assumptions about the charset of the XML MIME entity.
Omitting the charset parameter is NOT RECOMMENDED for application/... Omitting the charset parameter is not recommended for application/...
when used with transports other than HTTP or HTTPS---text/... SHOULD when used with transports other than HTTP or HTTPS. text/... should
NOT be used for 16-bit MIME with transports other than HTTP or HTTPS not be used for 16-bit MIME with transports other than HTTP or HTTPS
(see discussion above (Section 9.2, Paragraph 6)). (see discussion above (Section 9.2, Paragraph 6)).
9.5. Omitted Charset, no Internal Encoding Declaration and UTF-8 Entity 9.5. Omitted Charset, no Internal Encoding Declaration and UTF-8 Entity
Content-type charset: [none] Content-type charset: [none]
<?xml version='1.0'?> <?xml version='1.0'?>
In this example, the charset parameter has been omitted, the is no In this example, the charset parameter has been omitted, there is no
internal encoding declaration, and there is no BOM. Since there is internal encoding declaration, and there is no BOM. Since there is
no BOM, the XML processor follows the requirements in section 4.3.3, no BOM or charset parameter, the XML processor follows the
and optionally applies the mechanism described in Appendix F (which requirements in section 4.3.3, and optionally applies the mechanism
is non-normative) of [XML] to determine the charset encoding of described in Appendix F (which is non-normative) of [XML] to
UTF-8. Although the XML MIME entity does not contain an encoding determine the charset encoding of UTF-8. Although the XML MIME
declaration, the encoding actually _is_ UTF-8, so this is still a entity does not contain an encoding declaration, the encoding
conforming XML MIME entity. actually _is_ UTF-8, so this is still a conforming XML MIME entity.
An XML-unaware MIME processor SHOULD make no assumptions about the An XML-unaware MIME processor should make no assumptions about the
charset of the XML MIME entity. charset of the XML MIME entity.
See Section 9.1 for transport-related issues for UTF-8 XML MIME See Section 9.1 for transport-related issues for UTF-8 XML MIME
entities. entities.
9.6. UTF-16BE Charset 9.6. UTF-16BE Charset
Content-type charset: charset="utf-16be" Content-type charset: charset="utf-16be"
<?xml version='1.0' encoding='utf-16be'?> <?xml version='1.0' encoding='utf-16be'?>
Observe that the BOM does not exist. Since the charset parameter is Observe that the BOM does not exist. Since the charset parameter is
provided, MIME and XML processors MUST treat the enclosed entity as provided and there is no BOM, MIME and XML processors must treat the
UTF-16BE encoded. enclosed entity as UTF-16BE encoded.
See also the additional considerations in the UTF-16 example See also the additional considerations in the UTF-16 example
(Section 9.2) above. (Section 9.2) above.
9.7. Non-UTF Charset 9.7. Non-UTF Charset
Content-type charset: charset="iso-2022-kr" Content-type charset: charset="iso-2022-kr"
<?xml version="1.0" encoding="iso-2022-kr"?> <?xml version="1.0" encoding="iso-2022-kr"?>
This example shows the use of a non-UTF charset (in this case Hangul, This example shows the use of a non-UTF charset (in this case Hangul,
but this example is intended to cover all non-UTF-family charsets). but this example is intended to cover all non-UTF-family character
Since the charset parameter is provided, MIME processors MUST treat sets). Since the charset parameter is provided and there is no BOM,
the enclosed entity as encoded per RFC 1557. Since the XML MIME all processors must treat the enclosed entity as encoded per RFC
entity has an internal encoding declaration (this example does show 1557.
such a declaration, which agrees with the charset parameter) XML
processors MUST also treat the enclosed entity as encoded per RFC
1557. Thus, interoperability is assured.
Since ISO-2022-KR [RFC1557] has been defined to use only 7 bits of Since ISO-2022-KR [RFC1557] has been defined to use only 7 bits of
data, no content-transfer-encoding is necessary with any transport: data, no content-transfer-encoding is necessary with any transport:
for charsets needing 8 or more bits, considerations such as those for character sets needing 8 or more bits, considerations such as
discussed above (Section 9.1, Section 9.2) would apply. those discussed above (Section 9.1, Section 9.2) would apply.
9.8. Omitted Charset with Internal Encoding Declaration 9.8. Omitted Charset with Internal Encoding Declaration
Content-type charset: [none] Content-type charset: [none]
<?xml version='1.0' encoding="iso-10646-ucs-4"?> <?xml version='1.0' encoding="iso-10646-ucs-4"?>
In this example, the charset parameter has been omitted, and there is In this example, the charset parameter has been omitted, and there is
no BOM. However, the XML MIME entity does have an encoding no BOM. However, the XML MIME entity does have an encoding
declaration inside the XML MIME entity that specifies the entity's declaration inside the XML MIME entity that specifies the entity's
charset. Following the requirements in section 4.3.3, and optionally charset. Following the requirements in section 4.3.3, and optionally
applying the mechanism described in Appendix F (non-normative) of applying the mechanism described in Appendix F (non-normative) of
[XML], the XML processor determines the charset encoding of the XML [XML], the XML processor determines the charset encoding of the XML
MIME entity (in this example, UCS-4). MIME entity (in this example, UCS-4).
An XML-unaware MIME processor SHOULD make no assumptions about the An XML-unaware MIME processor should make no assumptions about the
charset of the XML MIME entity. charset of the XML MIME entity.
For charsets needing 8 or more bits, considerations such as those For character sets needing 8 or more bits, considerations such as
discussed above (Section 9.1, Section 9.2) would apply those discussed above (Section 9.1, Section 9.2) would apply
9.9. INCONSISTENT EXAMPLE: Conflicting Charset and Internal Encoding 9.9. INCONSISTENT EXAMPLE: Conflicting Charset and Internal Encoding
Declaration Declaration
Content-type charset: charset="utf-8" Content-type charset: charset="iso-8859-1"
<?xml version="1.0" encoding="iso-8859-1"?> <?xml version="1.0" encoding="utf-8"?>
Since the charset parameter is provided in the Content-Type header Although the charset parameter is provided in the Content-Type header
and differs from the XML encoding declaration, MIME and XML and there is no BOM and the charset parameter differs from the XML
processors will not interoperate. MIME processors will treat the encoding declaration, MIME and XML processors will interoperate.
enclosed entity as UTF-8 encoded. That is, the "iso-8859-1" encoding Since the charset parameter is authoritative in the absence of a BOM,
will be ignored. XML processors on the other hand will ignore the all processors will treat the enclosed entity as iso-8859-1 encoded.
charset parameter and treat the XML entity as encoded in iso-8859-1. That is, the "UTF-8" encoding declaration will be ignored.
Processors generating XML MIME entities MUST NOT label conflicting Processors generating XML MIME entities must not label conflicting
charset information between the MIME Content-Type and the XML charset information between the MIME Content-Type and the XML
declaration. In particular, the addition of an explicit, site-wide declaration unless they have definitive information about the actual
charset without inspecting the XML MIME entity has frequently lead to encoding, for example as a result of systematic transcoding. In
interoperability problems. particular, the addition by servers of an explicit, site-wide charset
default has frequently lead to interoperability problems for XML
documents.
9.10. INCONSISTENT EXAMPLE: Conflicting Charset and BOM
Content-type charset: charset="iso-8859-1"
{BOM}<?xml version="1.0"?>
Although the charset parameter is provided in the Content-Type
header, there is a BOM, so MIME and XML processors may not
interoperate. Since the BOM parameter is authoritative for XML
processors, they will treat the enclosed entity as UTF-16-encoded.
That is, the "iso-8859-1" charset parameter will be ignored. XML-
unaware MIME processors on the other hand may be unaware of the BOM
and so treat the entity as encoded in iso-8859-1.
Processors generating XML MIME entities must not label conflicting
charset information between the MIME Content-Type and an entity-
initial BOM.
10. IANA Considerations 10. IANA Considerations
As described in Section 8, this specification updates the [RFC6838]
and [RFC6839] registration process for XML-based MIME types. As described in Section 8, this specification updates the [RFC6839]
registration for XML-based MIME types (the "+xml" types).
11. Security Considerations 11. Security Considerations
XML MIME entities contain information which may be parsed and further XML MIME entities contain information which may be parsed and further
processed by the recipient's XML system. These entities may contain processed by the recipient. These entities may contain, and
and such systems may permit explicit system level commands to be recipients may permit, explicit system level commands to be executed
executed while processing the data. To the extent that an XML system while processing the data. To the extent that a recipient
will execute arbitrary command strings, recipients of XML MIME application executes arbitrary command strings from within XML MIME
entities may be a risk. In general, it may be possible to specify entities, they may be at risk.
commands that perform unauthorized file operations or make changes to
the display processor's environment that affect subsequent
operations.
In general, any information stored outside of the direct control of In general, any information stored outside of the direct control of
the user -- including CSS style sheets, XSL transformations, XML- the user -- including CSS style sheets, XSL transformations, XML-
entity declarations, and DTDs -- can be a source of insecurity, by entity declarations, and DTDs -- can be a source of insecurity, by
either obvious or subtle means. For example, a tiny "whiteout either obvious or subtle means. For example, a tiny "whiteout
attack" modification made to a "master" style sheet could make words attack" modification made to a "master" style sheet could make words
in critical locations disappear in user documents, without directly in critical locations disappear in user documents, without directly
modifying the user document or the stylesheet it references. Thus, modifying the user document or the stylesheet it references. Thus,
the security of any XML document is vitally dependent on all of the the security of any XML document is vitally dependent on all of the
documents recursively referenced by that document. documents recursively referenced by that document.
skipping to change at page 21, line 42 skipping to change at page 21, line 42
of security on the W3C's servers, or on any similarly trusted of security on the W3C's servers, or on any similarly trusted
repository. repository.
The simplest attack involves adding declarations that break The simplest attack involves adding declarations that break
validation. Adding extraneous declarations to a list of character validation. Adding extraneous declarations to a list of character
XML-entities can effectively "break the contract" used by documents. XML-entities can effectively "break the contract" used by documents.
A tiny change that produces a fatal error in a DTD could halt XML A tiny change that produces a fatal error in a DTD could halt XML
processing on a large scale. Extraneous declarations are fairly processing on a large scale. Extraneous declarations are fairly
obvious, but more sophisticated tricks, like changing attributes from obvious, but more sophisticated tricks, like changing attributes from
being optional to required, can be difficult to track down. Perhaps being optional to required, can be difficult to track down. Perhaps
the most dangerous option available to crackers is redefining default the most dangerous option available to attackers, when external DTD
values for attributes: e.g., if developers have relied on defaulted subsets or external parameter entities or other externally-specified
attributes for security, a relatively small change might expose defaulting is involved, is redefining default values for attributes:
enormous quantities of information. e.g. if developers have relied on defaulted attributes for security,
a relatively small change might expose enormous quantities of
information.
Apart from the structural possibilities, another option, "XML-entity Apart from the structural possibilities, another option, "XML-entity
spoofing," can be used to insert text into documents, vandalizing and spoofing," can be used to insert text into documents, vandalizing and
perhaps conveying an unintended message. Because XML permits perhaps conveying an unintended message. Because XML permits
multiple XML-entity declarations, and the first declaration takes multiple XML-entity declarations, and the first declaration takes
precedence, it's possible to insert malicious content where an XML- precedence, it is possible to insert malicious content where an XML-
entity reference is used, such as by inserting the full text of entity reference is used, such as by inserting the full text of
Winnie the Pooh in every occurrence of &mdash;. Winnie the Pooh in place of every occurrence of &mdash;.
Security considerations will vary by domain of use. For example, XML Security considerations will vary by domain of use. For example, XML
medical records will have much more stringent privacy and security medical records will have much more stringent privacy and security
considerations than XML library metadata. Similarly, use of XML as a considerations than XML library metadata. Similarly, use of XML as a
parameter marshalling syntax necessitates a case by case security parameter marshalling syntax necessitates a case by case security
review. review.
XML may also have some of the same security concerns as plain text. XML may also have some of the same security concerns as plain text.
Like plain text, XML can contain escape sequences that, when Like plain text, XML can contain escape sequences that, when
displayed, have the potential to change the display processor displayed, have the potential to change the display processor
skipping to change at page 23, line 43 skipping to change at page 23, line 42
6657, July 2012, 6657, July 2012,
<http://www.rfc-editor.org/rfc/rfc6657.txt>. <http://www.rfc-editor.org/rfc/rfc6657.txt>.
[RFC6838] Freed, N., Klensin, J., and T. Hansen, "Media Type [RFC6838] Freed, N., Klensin, J., and T. Hansen, "Media Type
Specifications and Registration Procedures", BCP 13, RFC Specifications and Registration Procedures", BCP 13, RFC
6838, January 2013. 6838, January 2013.
[RFC6839] Hansen, T. and A. Melnikov, "Additional Media Type [RFC6839] Hansen, T. and A. Melnikov, "Additional Media Type
Structured Syntax Suffixes", RFC 6839, January 2013. Structured Syntax Suffixes", RFC 6839, January 2013.
[XBase] Marsh, J. and R. Tobin, "XML Base", World Wide Web
Consortium Recommendation xmlbase, January 2009,
<http://www.w3.org/TR/xmlbase>.
[XML1.1] Bray, T., Paoli, J., Sperberg-McQueen, C.M., Maler, E., [XML1.1] Bray, T., Paoli, J., Sperberg-McQueen, C.M., Maler, E.,
Yergeau, F., and J. Cowan, "Extensible Markup Language Yergeau, F., and J. Cowan, "Extensible Markup Language
(XML) 1.1 (Second Edition)", World Wide Web Consortium (XML) 1.1 (Second Edition)", W3C Recommendation REC-xml,
Recommendation REC-xml, September 2006, September 2006,
<http://www.w3.org/TR/xml11>. <http://www.w3.org/TR/2006/REC-xml11-20060816/>.
Latest version available at
[XMLBase] Marsh, J. and R. Tobin, "XML Base (Second Edition)", W3C
Recommendation REC-xmlbase-20090128, January 2009,
<http://www.w3.org/TR/2009/REC-xmlbase-20090128/>.
Latest version available at
[XML] Bray, T., Paoli, J., Sperberg-McQueen, C.M., Maler, E., [XML] Bray, T., Paoli, J., Sperberg-McQueen, C.M., Maler, E.,
and F. Yergeau, "Extensible Markup Language (XML) 1.0 and F. Yergeau, "Extensible Markup Language (XML) 1.0
(Fifth Edition)", World Wide Web Consortium Recommendation (Fifth Edition)", W3C Recommendation REC-xml, November
REC-xml, November 2008, <http://www.w3.org/TR/REC-xml>. 2008, <http://www.w3.org/TR/2008/REC-xml-20081126/>.
Latest version available at
[XPointerElement] [XPointerElement]
Grosso, P., Maler, E., Marsh, J., and N. Walsh, "XPointer Grosso, P., Maler, E., Marsh, J., and N. Walsh, "XPointer
element() Scheme", World Wide Web Consortium element() Scheme", W3C Recommendation REC-XPointer-
Recommendation REC-XPointer-Element, March 2003, Element, March 2003,
<http://www.w3.org/TR/xptr-element/>. <http://www.w3.org/TR/2003/REC-xptr-element-20030325/>.
Latest version available at
[XPointerFramework] [XPointerFramework]
Grosso, P., Maler, E., Marsh, J., and N. Walsh, "XPointer Grosso, P., Maler, E., Marsh, J., and N. Walsh, "XPointer
Framework", World Wide Web Consortium Recommendation REC- Framework", W3C Recommendation REC-XPointer-Framework,
XPointer-Framework, March 2003, March 2003,
<http://www.w3.org/TR/xptr-framework/>. <http://www.w3.org/TR/2003/REC-xptr-framework-20030325/>.
Latest version available at
[XPtrRegPolicy]
Hazael-Massieux, D., "XPointer Scheme Name Registry
Policy", 2005,
<http://www.w3.org/2005/04/xpointer-policy.html>.
[XPtrReg] Hazael-Massieux, D., "XPointer Registry", 2005, [XPtrReg] Hazael-Massieux, D., "XPointer Registry", 2005,
<http://www.w3.org/2005/04/xpointer-schemes/>. <http://www.w3.org/2005/04/xpointer-schemes/>.
12.2. Informative References 12.2. Informative References
[ASCII] American National Standards Institute, "Coded Character [ASCII] American National Standards Institute, "Coded Character
Set -- 7-bit American Standard Code for Information Set -- 7-bit American Standard Code for Information
Interchange", ANSI X3.4, 1986. Interchange", ANSI X3.4, 1986.
[CSS] Bos, B., Lie, H.W., Lilley, C., and I. Jacobs, "Cascading
Style Sheets, level 2 (CSS2) Specification", World Wide
Web Consortium Recommendation REC-CSS2, May 1998,
<http://www.w3.org/TR/REC-CSS2/>.
[HTTPbis] Fielding, R., "Hypertext Transfer Protocol (HTTP/1.1) [HTTPbis] Fielding, R., "Hypertext Transfer Protocol (HTTP/1.1)
[revised]", ietf-httpbis-p1-messaging (work in progress), [revised]", ietf-httpbis-p2-semantics (work in progress),
February 2013. September 2013.
[ISO8859] ISO, "ISO-8859. International Standard -- Information [ISO8859] ISO, "ISO-8859. International Standard -- Information
Processing -- 8-bit Single-Byte Coded Graphic Character Processing -- 8-bit Single-Byte Coded Graphic Character
Sets -- Part 1: Latin alphabet No. 1, ISO-8859-1:1987", Sets -- Part 1: Latin alphabet No. 1, ISO-8859-1:1987",
1987. 1987.
[MediaFrags]
Troncy, R., Mannens, E., Pfeiffer, S., and D. Van Deursen,
"Media Fragments URI 1.0 (basic)", W3C Recommendation
media-frags, September 2012,
<http://www.w3.org/TR/2012/REC-media-frags-20120925/>.
Latest version available at
[RFC1557] Choi, U., Chon, K., and H. Park, "Korean Character [RFC1557] Choi, U., Chon, K., and H. Park, "Korean Character
Encoding for Internet Messages", RFC 1557, December 1993. Encoding for Internet Messages", RFC 1557, December 1993.
[RFC2130] Weider, C., Cecilia Preston, C., Simonsen, K., Alvestrand, [RFC2130] Weider, C., Cecilia Preston, C., Simonsen, K., Alvestrand,
H., Atkinson, R., Crispin, M., and P. Svanberg, "The H., Atkinson, R., Crispin, M., and P. Svanberg, "The
Report of the IAB Character Set Workshop held 29 February Report of the IAB Character Set Workshop held 29 February
- 1 March, 1996", RFC 2130, April 1997. - 1 March, 1996", RFC 2130, April 1997.
[RFC2376] Whitehead, E. and M. Murata, "XML Media Types", RFC 2376, [RFC2376] Whitehead, E. and M. Murata, "XML Media Types", RFC 2376,
July 1998. July 1998.
[RFC2703] Klyne, G., "Protocol-independent Content Negotiation [RFC2703] Klyne, G., "Protocol-independent Content Negotiation
Framework", RFC 2703, September 1999. Framework", RFC 2703, September 1999.
[RFC3023] Murata, M., St.Laurent, S., and D. Kohn, "XML Media [RFC3023] Murata, M., St.Laurent, S., and D. Kohn, "XML Media
Types", January 2001. Types", RFC 3023, January 2001.
[RFC3629] Yergeau, F., "UTF-8, a transformation format of ISO [RFC3629] Yergeau, F., "UTF-8, a transformation format of ISO
10646", RFC 3629, November 2003. 10646", RFC 3629, November 2003.
[RFC3977] Feather, B., "Network News Transfer Protocol", RFC 3977, [RFC3977] Feather, B., "Network News Transfer Protocol", RFC 3977,
October 2006. October 2006.
[RFC4289] Freed, N. and J. Klensin, "Multipurpose Internet Mail
Extensions (MIME) Part Four: Registration Procedures", RFC
4289, December 2005.
[RFC5321] Klensin, J., "Simple Mail Transfer Protocol", RFC 5321, [RFC5321] Klensin, J., "Simple Mail Transfer Protocol", RFC 5321,
October 2008. October 2008.
[RFC6152] Klensin, J., Freed, N., Rose, M., and D. Crocker, "SMTP [RFC6152] Klensin, J., Freed, N., Rose, M., and D. Crocker, "SMTP
Service Extension for 8-bit MIME Transport", RFC 6152, Service Extension for 8-bit MIME Transport", RFC 6152,
March 2011. March 2011.
[TAGMIME] Bray, T., Ed., "Internet Media Type registration, [TAGMIME] Bray, T., Ed., "Internet Media Type registration,
consistency of use", April 2004, consistency of use", April 2004,
<http://www.w3.org/2001/tag/2004/0430-mime>. <http://www.w3.org/2001/tag/2004/0430-mime>.
[XHTML] Pemberton, S. and et al, "XHTML 1.0: The Extensible [XHTML] Pemberton, S. and et al, "XHTML 1.0: The Extensible
HyperText Markup Language", World Wide Web Consortium HyperText Markup Language", W3C Recommendation xhtml1,
Recommendation xhtml1, December 1999, December 1999,
<http://www.w3.org/TR/xhtml1>. <http://www.w3.org/TR/2000/REC-xhtml1-20000126/>.
Latest version available at
Appendix A. Why Use the '+xml' Suffix for XML-Based MIME Types? Appendix A. Why Use the '+xml' Suffix for XML-Based MIME Types?
[RFC3023] contains a detailed discussion of the (at the time) novel [RFC3023] contains a detailed discussion of the (at the time) novel
use of a suffix, a practice which has since become widespread. use of a suffix, a practice which has since become widespread.
Interested parties are referred to [RFC3023], Appendix A. Interested parties are referred to [RFC3023], Appendix A.
Appendix B. Changes from RFC 3023 Appendix B. Changes from RFC 3023
There are numerous and significant differences between this There are numerous and significant differences between this
specification and [RFC3023], which it obsoletes. This appendix specification and [RFC3023], which it obsoletes. This appendix
summarizes the major differences only. summarizes the major differences only.
First, XPointer ([XPointerFramework] and [XPointerElement] has been First, XPointer ([XPointerFramework] and [XPointerElement] has been
added as fragment identifier syntax for "application/xml", and the added as fragment identifier syntax for "application/xml", and the
XPointer Registry ([XPtrReg]) mentioned. Second, [XBase] has been XPointer Registry ([XPtrReg]) mentioned. Second, [XMLBase] has been
added as a mechanism for specifying base URIs. Third, the language added as a mechanism for specifying base URIs. Third, the language
regarding charsets was updated to correspond to the W3C TAG finding regarding character sets was updated to correspond to the W3C TAG
Internet Media Type registration, consistency of use [TAGMIME]. finding Internet Media Type registration, consistency of use
Fourth, many references are updated, and the existence and relevance [TAGMIME]. Fourth, many references are updated, and the existence of
of XML 1.1 acknowledged. Finally, a number of justifications and and relevance of the spec. to XML 1.1 acknowledged. Finally, a
contextualizations which were appropriate when XML was new have been number of justifications and contextualizations which were
removed, including the whole of the original Appendix A. appropriate when XML was new have been removed, including the whole
of the original Appendix A.
Appendix C. Acknowledgements Appendix C. Acknowledgements
MURATA Makoto (FAMILY Given) and Alexey Melnikov made early and
important contributions to the effort to revise [RFC3023].
This specification reflects the input of numerous participants to the This specification reflects the input of numerous participants to the
ietf-xml-mime@imc.org mailing list, though any errors are the ietf-xml-mime@imc.org, xml-mime@ietf.org and apps-discuss@ietf.org
responsibility of the authors. Special thanks to: mailing lists, though any errors are the responsibility of the
authors. Special thanks to:
Mark Baker, James Clark, Dan Connolly, Martin Duerst, Ned Freed, Mark Baker, James Clark, Dan Connolly, Martin Duerst, Ned Freed,
Yaron Goland, Rick Jelliffe, Larry Masinter, David Megginson, Keith Yaron Goland, Bjoern Hoehrmann, Rick Jelliffe, Murray S. Kucherawy,
Moore, Chris Newman, Gavin Nicol, Marshall Rose, Jim Whitehead and Larry Masinter, David Megginson, S. Moonesamy, Keith Moore, Chris
participants of the XML activity and the TAG at the W3C. Newman, Gavin Nicol, Julian Reschke, Marshall Rose, Jim Whitehead,
Erik Wilde and participants of the XML activity and the TAG at the
W3C.
Jim Whitehead and Simon St.Laurent are editors of [RFC2376] and Jim Whitehead and Simon St.Laurent were editors of [RFC2376] and
[RFC3023], respectively. [RFC3023], respectively.
Authors' Addresses Authors' Addresses
Henry S. Thompson
University of Edinburgh
Email: ht@inf.ed.ac.uk
URI: http://www.ltg.ed.ac.uk/~ht/
Chris Lilley Chris Lilley
World Wide Web Consortium World Wide Web Consortium
2004, Route des Lucioles - B.P. 93 06902 2004, Route des Lucioles - B.P. 93 06902
Sophia Antipolis Cedex Sophia Antipolis Cedex
France France
Email: chris@w3.org Email: chris@w3.org
URI: http://www.w3.org/People/chris/ URI: http://www.w3.org/People/chris/
MURATA Makoto (FAMILY Given)
International University of Japan
Email: eb2m-mrt@asahi-net.or.jp
Alexey Melnikov
Isode Ltd.
Email: alexey.melnikov@isode.com
URI: http://www.melnikov.ca/
Henry S. Thompson
University of Edinburgh
Email: ht@inf.ed.ac.uk
URI: http://www.ltg.ed.ac.uk/~ht/
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