Internet DRAFT - draft-calconnect-vobject-i18n
draft-calconnect-vobject-i18n
Calendaring Extensions R. Tse
Internet-Draft P. Tam
Updates: 5545, 6321, 6350, 6351, 7953, Ribose
7265, 7095 (if approved) M. Douglass
Intended status: Standards Track Spherical Cow Group
Expires: December 10, 2018 June 8, 2018
vObject Internationalization
draft-calconnect-vobject-i18n-00
Abstract
This document specifies mechanisms for the internationalization of
vObject content and its realization in vFormat.
This document updates the following specifications:
o I-D.calconnect-vobject-vformat, The vObject Model and vFormat
Syntax
o RFC 6350, vCard version 4.0
o RFC 5545, Internet Calendaring and Scheduling Core Object
Specification (iCalendar)
o RFC 7953, Calendar Availability Extensions
This work is produced by the CalConnect TC-VCARD and TC-CALENDAR
committees.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
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Internet-Drafts are draft documents valid for a maximum of six months
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on December 10, 2018.
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Copyright Notice
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document authors. All rights reserved.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terms and Definitions . . . . . . . . . . . . . . . . . . . . 3
2.1. Definitions . . . . . . . . . . . . . . . . . . . . . . . 4
3. Property Parameter Usage Clarification: LANGUAGE . . . . . . 4
3.1. vFormat Implementation of LANGUAGE . . . . . . . . . . . 5
4. Property Parameter: SCRIPT . . . . . . . . . . . . . . . . . 5
4.1. vFormat Implementation of SCRIPT . . . . . . . . . . . . 6
5. Property Parameter: PHONETIC . . . . . . . . . . . . . . . . 6
5.1. vFormat Implementation of PHONETIC . . . . . . . . . . . 7
6. Security Considerations . . . . . . . . . . . . . . . . . . . 7
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
7.1. iCalendar and vCard Property Parameter Registration:
SCRIPT . . . . . . . . . . . . . . . . . . . . . . . . . 8
7.2. iCalendar and vCard Property Parameter Registration:
PHONETIC . . . . . . . . . . . . . . . . . . . . . . . . 8
7.3. iCalendar and vCard Registration for Value Data Type:
SCRIPT-CODE . . . . . . . . . . . . . . . . . . . . . . . 9
7.4. iCalendar and vCard Registration for Value Data Type:
PHONETIC-CODE . . . . . . . . . . . . . . . . . . . . . . 9
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 10
8.1. Normative References . . . . . . . . . . . . . . . . . . 10
8.2. Informative References . . . . . . . . . . . . . . . . . 10
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 12
1. Introduction
vCard [RFC6350] and iCalendar [RFC5545] are standards compliant to
the vObject data model [I-D.calconnect-vobject-vformat-03].
These standards are used worldwide and require proper certain
localization elements suitable for multi-cultural use.
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Previously, the only internationalization method for vCard [RFC6350]
and iCalendar [RFC5545] standards was the "language" property
parameter (3.2.10 [RFC5545]).
This document:
o defines additional internationalization features for the vObject
data model, including a separate property parameter that denotes
the script used in a property value, and a method to specify
pronunciation of a property value
o defines realization methods of vObject internationalization in
vFormat
The methods described in this document are intended to be used by
vObject-compliant standards, such as vCard 4.0 [RFC6350] and
iCalendar [RFC5545].
This is a work product of the CalConnect TC-VCARD [CALCONNECT-VCARD]
and TC-CALENDAR [CALCONNECT-CALENDAR] committees.
2. Terms and Definitions
The key words "*MUST*", "*MUST NOT*", "*REQUIRED*", "*SHALL*",
"*SHALL NOT*", "*SHOULD*", "*SHOULD NOT*", "*RECOMMENDED*", "*NOT
RECOMMENDED*", "*MAY*", and "*OPTIONAL*" in this document are to be
interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only
when, they appear in all capitals, as shown here.
The key words "*Private Use*", "*Experimental Use*", "*Hierarchical
Allocation*", "*First Come First Served*", "*Expert Review*",
"*Specification Required*", "*RFC Required*", "*IETF Review*",
"*Standards Action*" and "*IESG Approval*" in this document are to be
interpreted as described in 4 [RFC8126].
Notation in this document is described in ABNF [RFC5234] as used by
[RFC6350].
Definitions from [RFC6350] apply to this specification except when
explicitly overridden.
All names of properties, property parameters, enumerated property
values, and property parameter values are case-insensitive. However,
all property values are case-sensitive, unless otherwise stated.
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2.1. Definitions
phonetic system
method of transcription of language in a script that allows
phonetic reproduction
3. Property Parameter Usage Clarification: LANGUAGE
This section clarifies the intent of the "LANGUAGE" property
parameter in [RFC5545] and [RFC6350] to be for the identification of
the language used in the property value where the parameter is
specified.
The [RFC5646] defined "language-tag" allows specification of multiple
attributes (called "subtags") in addition to just language. Its
basic form includes:
o a mandatory language subtag, using a language identifier from ISO
639 (-2, -3) (called a "primary" or "extended" language subtag)
o an optional script subtag, using a script identifier from ISO
15924
o an optional region subtag, using country codes listed in ISO 3166
or a UN numeric code
o one or more, optional, variant and extension subtags defined in
the IANA language subtag registry.
In practical usage of vObject standards, including [RFC5545] and
[RFC6350], it is determined that the combinatorial enumeration of
non-language subtags often cause unnecessary confusion in
interpretation and parsing, especially when the registry contain
variant and extension subtags that either conflict in semantics or
have overly restrictive in their supported prefixes.
This document therefore clarifies the intent of 3.2.10 [RFC5545] and
5.1 [RFC6350], such that the "LANGUAGE" property parameter *SHOULD*
only support the mandatory language subtag.
Other subtags *MAY* be supplied as specified in [RFC5646], but they
are purely for informational purposes not used in the vObject
specification.
Namespace
Property parameter name
"LANGUAGE"
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Purpose
To specify the language used in the property value.
Value type
"LANGUAGE-TAG" 4.8 [RFC6350]
Description
As provided above.
3.1. vFormat Implementation of LANGUAGE
The value of the "LANGUAGE" property parameter is re-defined as shown
below.
Format definition
languageparam = "LANGUAGE" "=" language *(subpart)
language = iso-639-3-code / iso-639-2-code
; a 2-alpha or 3-alpha language code
; defined in ISO 639
subpart = "-" *alphanum
; all other subparts unsupported
Examples
N;LANGUAGE=en:Miyazaki;Hayao;;;
N;LANGUAGE=jp:宮崎;駿;;;
4. Property Parameter: SCRIPT
The "SCRIPT" property parameter specifies the written script used in
the property value which contains the parameter, which is amongst the
valid codes in the ISO 15924 registry.
It is separated from the "LANGUAGE" property parameter defined in
[RFC5545] and [RFC6350] for reasons stated in Section 3.
Namespace
Property parameter name
SCRIPT
Purpose
To specify the script used in the property value, which is amongst
the valid codes in the ISO 15924 registry.
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Value type
TEXT, a single value valid in the ISO 15924 script registry.
Description
The property value of which this property parameter applies to
must have identical structure to
4.1. vFormat Implementation of SCRIPT
Format definition
scriptparam = "SCRIPT" "=" script-code
; script-code defined in the value type SCRIPT-CODE
Examples
N;SCRIPT=Hira;LANGUAGE=jp:みやざき;はやお;;;
N;SCRIPT=Hani;LANGUAGE=jp:宮崎;駿;;;
5. Property Parameter: PHONETIC
A number of contact managers have long used "X-properties" to to
store phonetic information of a vCard's subject, such as "X-PHONETIC-
NAME", "X-PHONETIC-FIRST-NAME" and "X-PHONETIC-LAST-NAME".
However, this is an issue for multiple reasons:
o The value of the X-property does not define the phonetic system
used for its transcription;
o This X-property usage does not enable interoperability since it
does not require specification of the language transcribed, as
well as the script of the resulting transcription;
o The scheme of using X-properties does not allow representation of
phonetics on other vCard values.
This section defines three property parameters used to store
pronunciation information of a property value:
1. The script used in the pronunciation system;
2. An identifier of the pronunciation system used;
3. The source language that was transcribed by the pronunciation
system.
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The "PHONETIC" property parameter specifies the phonetic system used
in the transcription of the property value, identified by the
phonetic system code from the ISO XXXXX phonetic system registry.
This property parameter is often applied together with the "LANGUAGE"
(Section 3) and "SCRIPT" (Section 4) property parameters.
Namespace
Property parameter name
PHONETIC
Purpose
To specify the phonetic system used in the property value, which
is amongst the valid codes in the ISO XXXXX registry.
Value type
TEXT, a single value valid in the ISO XXXXX phonetic system
registry.
Description
The property value of which this property parameter applies to
must take an identical structure to the property value without
application of this property parameter.
5.1. vFormat Implementation of PHONETIC
Format definition
phoneticparam = "PHONETIC" "=" phonetic
phonetic = 4ALPHA ; ISO XXXXX 4-digit phonetic system code
Examples
N;SCRIPT=Hant;LANGUAGE=zho:孫;中山;文,逸仙;;
N;SCRIPT=Hans;LANGUAGE=zho:孙;中山;文,逸仙;;
N;PHONETIC=jyut;SCRIPT=Latn;LANGUAGE=yue:syun1;zung1saan1;man4,jat6sin1;;
N;PHONETIC=ping;SCRIPT=Latn;LANGUAGE=cmn:sun;zhongshan;rixian;;
6. Security Considerations
Security considerations of the vObject formats themselves *MUST* be
adhered to, including:
o vCard: [RFC6350]
o iCalendar: [RFC5545], [RFC4791]
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o vObject: [I-D.calconnect-vobject-vformat-03]
vObject formats, especially for calendaring, scheduling and contact
exchange, often involve privacy-sensitive information.
Internationalization features defined in this document *MAY* pose
risk of exposing private information if interchanged through
unprotected communication channels.
Mechanisms used for the transmission of such information should
implement security measures to protect against possible threats, such
as eavesdropping, replay, message insertion, deletion, modification,
and man-in-the-middle attacks.
7. IANA Considerations
IANA is requested to register the following property parameters and
value types in the corresponding iCalendar and vCard registries.
7.1. iCalendar and vCard Property Parameter Registration: SCRIPT
Namespace
Parameter name
SCRIPT
Purpose
Given in Section 4.
Description
Given in Section 4.
Format definition
Given in Section 4.
Examples
Given in Section 4.
7.2. iCalendar and vCard Property Parameter Registration: PHONETIC
Namespace
Parameter name
PHONETIC
Purpose
Given in Section 5.
Description
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Given in Section 5.
Format definition
Given in Section 5.
Examples
Given in Section 5.
7.3. iCalendar and vCard Registration for Value Data Type: SCRIPT-CODE
Value name
SCRIPT-CODE
Purpose
Indicate script used in property value using a valid value from
the ISO 15924 registry.
Description
Used by the SCRIPT property parameter.
Format definition
script-code = 4ALPHA
; ISO 15924 4-digit script code
Examples
"Latn", "Cyrl", "Hani"
7.4. iCalendar and vCard Registration for Value Data Type: PHONETIC-
CODE
Value name
PHONETIC-CODE
Purpose
Indicate phonetic system used in the transcription of property
value, using a valid value from the ISO XXXXX registry.
Description
Used by the SCRIPT property parameter.
Format definition
phonetic-code = 4ALPHA
; ISO XXXXX 4-digit script code
Examples
"ipa", "jyut", "ping"
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8. References
8.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66,
RFC 3986, DOI 10.17487/RFC3986, January 2005,
<https://www.rfc-editor.org/info/rfc3986>.
[RFC5545] Desruisseaux, B., Ed., "Internet Calendaring and
Scheduling Core Object Specification (iCalendar)",
RFC 5545, DOI 10.17487/RFC5545, September 2009,
<https://www.rfc-editor.org/info/rfc5545>.
[RFC5646] Phillips, A., Ed. and M. Davis, Ed., "Tags for Identifying
Languages", BCP 47, RFC 5646, DOI 10.17487/RFC5646,
September 2009, <https://www.rfc-editor.org/info/rfc5646>.
[RFC6350] Perreault, S., "vCard Format Specification", RFC 6350,
DOI 10.17487/RFC6350, August 2011,
<https://www.rfc-editor.org/info/rfc6350>.
[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/info/rfc8126>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
8.2. Informative References
[CALCONNECT-CALENDAR]
The Calendaring and Scheduling Consortium, "CalConnect
CALENDAR Technical Committee", April 2018,
<https://www.calconnect.org/about/technical-committees/
calendar-technical-committee>.
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[CALCONNECT-VCARD]
The Calendaring and Scheduling Consortium, "CalConnect
VCARD Technical Committee", April 2018,
<http://www.calconnect.org/about/technical-committees/
vcard-technical-committee>.
[I-D.calconnect-vobject-vformat-03]
Tse, R., Tam, P., Daboo, C., and K. Murchison, "The
vObject Model and vFormat Syntax", draft-calconnect-
vobject-vformat-03 (work in progress), June 2018.
[RFC4791] Daboo, C., Desruisseaux, B., and L. Dusseault,
"Calendaring Extensions to WebDAV (CalDAV)", RFC 4791,
DOI 10.17487/RFC4791, March 2007,
<https://www.rfc-editor.org/info/rfc4791>.
[RFC5234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", STD 68, RFC 5234,
DOI 10.17487/RFC5234, January 2008,
<https://www.rfc-editor.org/info/rfc5234>.
[RFC6321] Daboo, C., Douglass, M., and S. Lees, "xCal: The XML
Format for iCalendar", RFC 6321, DOI 10.17487/RFC6321,
August 2011, <https://www.rfc-editor.org/info/rfc6321>.
[RFC6351] Perreault, S., "xCard: vCard XML Representation",
RFC 6351, DOI 10.17487/RFC6351, August 2011,
<https://www.rfc-editor.org/info/rfc6351>.
[RFC6352] Daboo, C., "CardDAV: vCard Extensions to Web Distributed
Authoring and Versioning (WebDAV)", RFC 6352,
DOI 10.17487/RFC6352, August 2011,
<https://www.rfc-editor.org/info/rfc6352>.
[RFC7095] Kewisch, P., "jCard: The JSON Format for vCard", RFC 7095,
DOI 10.17487/RFC7095, January 2014,
<https://www.rfc-editor.org/info/rfc7095>.
[RFC7265] Kewisch, P., Daboo, C., and M. Douglass, "jCal: The JSON
Format for iCalendar", RFC 7265, DOI 10.17487/RFC7265, May
2014, <https://www.rfc-editor.org/info/rfc7265>.
[RFC7953] Daboo, C. and M. Douglass, "Calendar Availability",
RFC 7953, DOI 10.17487/RFC7953, August 2016,
<https://www.rfc-editor.org/info/rfc7953>.
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[RFC7986] Daboo, C., "New Properties for iCalendar", RFC 7986,
DOI 10.17487/RFC7986, October 2016,
<https://www.rfc-editor.org/info/rfc7986>.
[RFC8259] Bray, T., Ed., "The JavaScript Object Notation (JSON) Data
Interchange Format", STD 90, RFC 8259,
DOI 10.17487/RFC8259, December 2017,
<https://www.rfc-editor.org/info/rfc8259>.
Authors' Addresses
Ronald Henry Tse
Ribose
Suite 1111, 1 Pedder Street
Central
Hong Kong
Email: ronald.tse@ribose.com
URI: https://www.ribose.com
Peter Kwan Yu Tam
Ribose
Suite 1111, 1 Pedder Street
Central
Hong Kong
Email: peter.tam@ribose.com
URI: https://www.ribose.com
Mike Douglass
Spherical Cow Group
226 3rd Street
Troy, NY 12180
United States of America
Email: mdouglass@sphericalcowgroup.com
URI: http://sphericalcowgroup.com
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