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CVS libidn/doc/specifications
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libidn-commit |
Subject: |
CVS libidn/doc/specifications |
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Thu, 12 Jan 2006 22:44:43 +0100 |
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draft-xdlee-idn-cdnadmin-06.txt
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2006/01/12 21:44:43 1.1
Network Working Group X. LEE
Internet-Draft E. CHEN
Expires: July 16, 2006 J. KLENSIN
N. HSU
W. MAO
Jan. 12, 2006
Registration and Administration Guideline for Chinese Domain Names
draft-xdlee-idn-cdnadmin-06.txt
Status of this Memo
By submitting this Internet-Draft, each author represents that any
applicable patent or other IPR claims of which he or she is aware
have been or will be disclosed, and any of which he or she becomes
aware will be disclosed, in accordance with Section 6 of BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as Internet-
Drafts.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html.
This Internet-Draft will expire on July 16, 2006.
Copyright Notice
Copyright (C) The Internet Society (2006).
Abstract
Many Chinese characters in common use have variants, which makes most
of the Chinese Domain Names (CDN) have at least two different forms.
The equivalence between Simplified Chinese (SC) and Traditional
Chinese (TC) characters is very important for CDN registration. This
memo defines some basic concepts and specifies the proposed
registration and administration procedure of Chinese domain names
LEE, et al. Expires July 16, 2006 [Page 1]
Internet-Draft Guideline for Chinese Domain Names Jan. 2006
based on the more general guidelines of RFC 3743 to avoid the
problems that may be caused by the variants. It will be useful for
understanding and using the tables defined in [LVT-SC] and [LVT-TC].
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.1. Chinese Characters . . . . . . . . . . . . . . . . . . . . 4
2.2. Chinese Domain Name Label (CDNL) . . . . . . . . . . . . . 4
2.3. Simplified Chinese Variant Table (SCVT) . . . . . . . . . . 4
2.4. Traditional Chinese Variant Table (TCVT) . . . . . . . . . 4
2.5. Original Chinese Domain Name Label (OCDNL) . . . . . . . . 4
3. Procedure for CDNLs registration . . . . . . . . . . . . . . . 5
4. Security Considerations . . . . . . . . . . . . . . . . . . . . 6
5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 7
6. References . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 8
Intellectual Property and Copyright Statements . . . . . . . . . . 9
LEE, et al. Expires July 16, 2006 [Page 2]
Internet-Draft Guideline for Chinese Domain Names Jan. 2006
1. Introduction
With the standard of Internationalized Domain Names for Application
(IDNA, described in [RFC3490], [RFC3491] and [RFC3492]), non-ASCII
characters are included in the DNS, and users can access Internet
with their native languages, most of which are not English. However,
many languages have special requirements, which are not addressed in
the IDNA RFCs. For example, changes were made in the forms of a
large number of Chinese characters during the last century to
simplify writing and reading. These "Simplified" character have been
adopted in some Chinese-speaking communities, while others continue
to use the "Traditional" forms. On the global Internet, if IDNA were
used alone, there would be considerable potential for confusion if
the two forms were not considered together. Consequently, effective
use of Chinese domain names (CDN) requires variant equivalence, as
described in [RFC3743], to handle character differences between
Simplified and Traditional Chinese forms.
Theoretically, Chinese variant equivalence itself is very complicated
(Please read [C2C] for further information). When it comes to the
usage of Chinese domain names, the basic requirement is to match the
user perception of Chinese characters between Simplified Chinese (SC)
and Traditional Chinese (TC) forms. When users register SC/TC domain
names, they do wish to obtain the traditional/simplified forms as
well, and expect others to be able to access the website in both
forms.
This document specifies a solution for Chinese domain name
registration and administration that has been adopted and deployed to
manage Simplified Chinese and Traditional Chinese domain name
equivalence. This solution, based on [RFC3743], is suitable for any
DNS zone manager or registrar who provides Chinese domain names
service. In the terminology of [RFC3743], this solution is IDL-based
(Internationalized Domain Label).
LEE, et al. Expires July 16, 2006 [Page 3]
Internet-Draft Guideline for Chinese Domain Names Jan. 2006
2. Terminology
This document adopts the terminologies that are defined in [RFC3743]
and it is not possible to understand this document without first
understanding its concepts and terminology, including terminology
introduced in its examples. Additional terminology is defined later
in this document.
2.1. Chinese Characters
This document suggests permitting only a subset of Chinese characters
in CDN, i.e., in the DNS. When this document discusses Chinese
characters, it only refers to a subset of the characters in the first
column of the tables in 3.3 and 3.4. These are defined, in detail,
in [LVT-SC] and [LVT-TC]. Of course, this doesn't suggest those
excluded from these tables are not Chinese characters. However, it
strongly suggests that registries do not permit any registration of
Chinese characters that are not listed in these tables. These tables
will be updated in the future if necessary.
2.2. Chinese Domain Name Label (CDNL)
If an IDN label includes at least one Chinese character, it is called
a Chinese Domain Name (CDN) Label. CDN labels may contain characters
from the traditional letter-digit-hyphen (LDH) set as well as Chinese
characters.
2.3. Simplified Chinese Variant Table (SCVT)
Based on [RFC3743], a language table for Simplified Chinese has been
defined [LVT-SC]. It can be used for the registration of Simplified
Chinese domain names. The key feature of this table is that the
preferred variant is the SC character, which is used by Mainland
China users or defined in Chinese related standards.
2.4. Traditional Chinese Variant Table (TCVT)
Similarly, a language table has been defined for Traditional Chinese
[LVT-TC]. It is also based on the rules of [RFC3743]. It can be
used for registration of Traditional Chinese domain names. The
preferred variant is the TC character, which is used in Taiwan or
defined in related standards.
2.5. Original Chinese Domain Name Label (OCDNL)
The CDNL that users submit for registration.
LEE, et al. Expires July 16, 2006 [Page 4]
Internet-Draft Guideline for Chinese Domain Names Jan. 2006
3. Procedure for CDNLs registration
This document adopts the same procedure for CDNLs registration as the
one defined for more general IDN labels in section 3.2.3 of
[RFC3743].
The first column of SCVT is same as the first column of TCVT, so are
the third columns of both tables, so the CV(IN, ZH-CN) will be same
as the CV(IN, ZH-TW) after Step 3; The PV(IN, ZH-CN) is SC form, and
the PV(IN, ZH-TW) is TC form. As result, there will be not more than
three records, including OCDNL, SC form and TC form to be added into
zone file after this procedure.
The set of languages associated with IN is both ZH-CN and ZH-TW by
default. The procedure for CDNL registration uses the registry-
defined rules for optional processing, with the understanding that
the rules may vary for different registries supporting CDNs. The
motivation for such rules is described below.
The preferred variant(s) is/are TC in TCVT, and SC in SCVT. There
may be more than one preferred variant for a given valid character.
In actuality, while IDNA, and hence [RFC3743], look at characters one
at a time, the actual relationship between the valid code point and
the preferred variant is contextual: whether one character can be
substituted for another depends on the characters with which it is
associated in a label or, more generally, in a phrase. In
particular, some of the preferred variants make no sense in
combination with other characters; therefore, those combinations
should not be added into the Zone file as ZV. If desired, it should
be possible to define and implement rules to reduce the preferred
variant labels to only plausible ones. This could be done, for
example, with some artificial intelligence tools, or with feedback
from the registrant, or with selection based on frequency of
occurrence in other texts. To illustrate one possibility, the OCDNL
could be required to be TC-only or SC-only, and if there are more
than one preferred variants, the OCDNL will be used as the PV,
instead of PV produced by the algorithm.
To reemphasize, the tables in [LVT-SC] and [LVT-TC] follow the table
format and terminologies defined in [RFC3743]. If one intends to
implement Chinese domain names registration based on these two tables
or ones similar to them, a complete understanding of [RFC3743] is
needed for the proper use of those tables.
LEE, et al. Expires July 16, 2006 [Page 5]
Internet-Draft Guideline for Chinese Domain Names Jan. 2006
4. Security Considerations
This document is subject to the same security considerations as
[RFC3743], which defines the table formats and operations. As with
that base document, part of its intent is to reduce the security
problems that might be caused by confusion among characters with
similar appearances or meanings. While it will not introduce any
additional security issues, additional registration restrictions such
as those outlined in section 3 may further help reduce potential
problems.
LEE, et al. Expires July 16, 2006 [Page 6]
Internet-Draft Guideline for Chinese Domain Names Jan. 2006
5. Acknowledgements
Thanks for these person's suggestions, promotions and efforts on such
tough work: WANG YanFeng, Ai-Chin LU, Shian-Shyong TSENG, QIAN
HuaLin, and Li-Ming TSENG.
Especially, thanks Joe ZHANG and XiaoMing WANG for their outstanding
contributions on SCVT in [LVT-SC]. And also thanks Kenny HUANG,
Zheng-Wei LIN, Shi-Xiong TSENG, Lie-Neng WU, Cheng-Wu PAN, Lin-Mei
WEI, Qi-Qing HSU for their efforts and contributions on editing the
TCVT in [LVT-TC]. These experts provided basic materials, or gave
very crucial suggestions and principles to accomplish these two
variant tables.
And that, the authors gratefully acknowledge the contributions of
those who commented and make suggestions on this document, including
James SENG, and other JET members.
6. References
[C2C] Halpern, J. and J. Kerman, "Pitfalls and Complexities of
Chinese to Chinese Conversion", International Unicode
Conference (14th) in Boston, March 1999.
[LVT-SC] QIAN, H. and X. LEE, ".CN Chinese Character Table",
IANA IDN Languages Tables, March 2005.
[LVT-TC] LU, A., ".TW Traditional Chinese Character Table",
IANA IDN Languages Tables, March 2005.
[RFC3490] Faltstrom, P., Hoffman, P., and A. Costello,
"Internationalizing Domain Names in Applications (IDNA)",
RFC 3490, March 2003.
[RFC3491] Hoffman, P. and M. Blanchet, "Nameprep: A Stringprep
Profile for Internationalized Domain Names (IDN)",
RFC 3491, March 2003.
[RFC3492] Costello, A., "Punycode: A Bootstring encoding of Unicode
for Internationalized Domain Names in Applications
(IDNA)", RFC 3492, March 2003.
[RFC3743] KONISHI, K., HUANG, K., QIAN, H., and Y. KO, "Joint
Engineering Team (JET) Guidelines for Internationalized
Domain Names (IDN) Registration and Administration for
Chinese, Japanese, and Korean", RFC 3743, April 2004.
LEE, et al. Expires July 16, 2006 [Page 7]
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Authors' Addresses
LEE Xiaodong
CNNIC, No.4 South 4th Street, Zhongguancun
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