RFC 4713

Registration and Administration Recommendations for Chinese Domain Names

📅 published October 2006, from ietf

Registration and Administration Recommendations for Chinese Domain Names 🎀

okay bestie, this one is RFC 4713 💅 It's titled Registration and Administration Recommendations for Chinese Domain Names, and it's published in the Network Working Group series, dated October 2006. The category is Informational ✨, which means it's sharing info with the Internet community, not an Internet standard. The authors are X. Lee, W. Mao, E. Chen, N. Hsu, and J. Klensin, with CNNIC and TWNIC showing up as affiliations 🫶 The header doesn't list anything it obsoletes or updates, so it's standing on its own 🦋

Status of This Memo ✨

this memo gives info to the Internet community 💖 it does not specify an Internet standard of any kind, and it's free to distribute with no limits 🌸

Copyright Notice 🎀

IESG Note 🙈

okay, serious moment ⚠️ this RFC is not a candidate for any level of Internet Standard. The IETF doesn't vouch for whether it fits any purpose 💀 The decision to publish was not based on IETF review for things like security, congestion control, or inappropriate interaction with deployed protocols. The RFC Editor chose to publish it at their discretion, so readers should be careful about how much they lean on it for implementation and deployment. See RFC 3932 for more info 🧚

Abstract ✨

okay so here's the tea 🍓 many Chinese characters in common use have variants, which means most Chinese Domain Names (CDNs) come in at least two different forms 🌈 The equivalence between Simplified Chinese (SC) and Traditional Chinese (TC) characters is super important for CDN registration 😭 This memo builds on the basic concepts, general guidelines, and framework of RFC 3743 to lay out proposed registration and administration procedures for Chinese domain names 💜 It also gives the info you need to understand and use the tables defined in the IANA table registrations for Simplified and Traditional Chinese 👑

Table of Contents 🧚

   1. Introduction ....................................................2
   2. Terminology .....................................................3
      2.1. Chinese Characters .........................................3
      2.2. Chinese Domain Name Label (CDNL) ...........................3
      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 Registration of Chinese Domain Name Labels ........4
      3.1. Terminology and Context ....................................4
      3.2. Procedure in Terms of the RFC 3743 Model ...................4
      3.3. RFC 3743 Optional Registry Processing ......................5
   4. Security Considerations .........................................5
   5. Acknowledgements ................................................6
   6. References ......................................................6
      6.1. Normative References .......................................6
      6.2. Informative References .....................................7

1. Introduction ✨

okay so IDNA (described in [RFC3490], [RFC3491], and [RFC3492]) is what made internationalized domain names (IDNs) possible 🌸 IDNs are the ones with non-ASCII characters, and they get included in the DNS so people can reach the Internet in their native languages, which mostly aren't English 🦋 but lowkey, many languages have special needs that the IDNA RFCs don't cover 😭 One way to handle some of what's left is to group characters that could get confused with each other as "variants" 🫶 The variant approach is covered in RFC 4290 [RFC4290], and for documents written in Chinese, Japanese, or Korean (CJK documents) there's the so-called "JET Guidelines" in RFC 3743 [RFC3743] 💅 Readers of this doc are assumed to already know the concepts and terminology of RFC 3743 🧚 The guidelines in this document give a set of specific tables and methods that are needed to apply the JET Guidelines to Chinese characters 💖

Here's the vibe: a big pile of Chinese characters got changed during the last century to make writing and reading easier ✨ These "Simplified" characters were adopted in some Chinese-speaking communities, while others kept using the "Traditional" forms 🌈 On the global Internet, if IDNA were used alone, there'd be a lot of room for confusion if the two forms weren't considered together 🙈 So effective use of Chinese Domain Names (CDNs) needs variant equivalence, like RFC 3743 describes, to handle the character differences between Simplified and Traditional Chinese forms 👑

Chinese variant equivalence is seriously complicated in principle (go read [C2C] if you want the full story) 🤓 When it comes to actually using Chinese domain names, the basic need is to match what users perceive as the same Chinese characters between Simplified Chinese (SC) and Traditional Chinese (TC) forms 💜 When users register an SC or TC domain name, they'll want the other form too, and they'll expect everyone to be able to reach the website or other resources in both forms 🎀

This document specifies a solution for Chinese domain name registration and administration that CNNIC (the top-level domain registry for "CN") and TWNIC (the top-level domain registry for "TW") have adopted and deployed to manage Simplified and Traditional Chinese domain name equivalence 🔥 In RFC 3743's terminology, this solution is based on Internationalized Domain Labels (IDLs) 🧚

2. Terminology 💅

this doc adopts the terminology defined in RFC 3743 🌸 You really can't understand this document without first understanding the concepts and terminology of RFC 3743, including the terms it introduces in its examples 🫶 Any additional terminology is defined later on in this doc ✨

2.1. Chinese Characters 🎀

This document suggests permitting only a subset of Chinese characters in Chinese Domain Names (CDNs), and therefore in the DNS 🦋 When this document talks about Chinese characters, it only means the subset in the first column of the current IANA registration tables for Chinese, as discussed in Section 2.3 and Section 2.4 💖 Those are defined in detail in [LVT-SC] and [LVT-TC] 👑 Of course, characters left out of these tables are still valid Chinese characters, obviously 💅 But this document strongly suggests that registries do not permit any registration of Chinese characters that aren't listed in the tables 🙈 The tables themselves will get updated in the future if needed 🌈

2.2. Chinese Domain Name Label (CDNL) 🌸

If an IDN label includes at least one Chinese character, it's called a Chinese Domain Name (CDN) Label 💜 CDN labels can contain characters from the traditional letter-digit-hyphen (LDH) set as well as Chinese characters ✨

2.3. Simplified Chinese Variant Table (SCVT) 🦋

Based on RFC 3743 [RFC3743], a language table for Simplified Chinese has been defined in [LVT-SC] 🫶 It can be used to register Simplified Chinese domain names 💖 The key feature of this table is that the preferred variant is the SC character, which is used by Chinese mainland users or defined in Chinese-related standards 👑

2.4. Traditional Chinese Variant Table (TCVT) 🎀

Similarly, a language table has been defined for Traditional Chinese in [LVT-TC] 🌈 It's also based on the rules of RFC 3743 🧚 It can be used to register Traditional Chinese domain names 🍓 The preferred variant is the TC character, which is used by Taiwan users or defined in related standards 💅

2.5. Original Chinese Domain Name Label (OCDNL) 💜

This is the Chinese Domain Name Label that users submit for registration 🌸

3. Procedure for Registration of Chinese Domain Name Labels 🔥

3.1. Terminology and Context ✨

okay so this document uses the same procedure for Chinese Domain Name Label (CDNL) registration as the one defined for more general IDN labels in section 3.2.3 of RFC 3743 [RFC3743] 🦋 The terminology, notation, and steps mentioned below all come from that doc 🫶 In particular, "CV" is the character variant associated with an input character ("IN") and a language table 💖 The language tables used here are the ones for Chinese as spoken and written in the Chinese mainland (ZH-CN) and in Taiwan (ZH-TW) 👑 And "PV" is the selected Preferred Variant 💅

3.2. Procedure in Terms of the RFC 3743 Model 🌈

The first column of the Simplified Chinese Variant Table (SCVT) is the same as the first column of the matching Traditional Chinese Variant Table (TCVT), and so are the third columns of both tables 🎀 So CV(IN, ZH-CN) ends up being the same as CV(IN, ZH-TW) after Step 3 🧚 The PV(IN, ZH-CN) is in SC form, and the PV(IN, ZH-TW) is in TC form 🌸 This means there won't be more than three records (the original label (OCDNL), the Simplified Chinese (SC) form, and the Traditional Chinese (TC) form) added to the zone file after applying this procedure ✨ In other words, the procedure does not generate labels that mix Simplified and Traditional Chinese as variants 🔥

The set of languages associated with the input (IN) is both ZH-CN and ZH-TW by default 💖 The CDNL registration procedure uses the optional registry-defined rules that RFC 3743 provides for optional processing, with the understanding that those rules may vary between registries that support CDNs 🦋 The motivation for those 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 💅

3.3. RFC 3743 Optional Registry Processing 💜

Here's the real talk 🙈 IDNA, and therefore RFC 3743, processes characters one at a time, but the actual relationship between a valid code point and its preferred variant is contextual 🌈 Whether one character can be swapped for another depends on which characters it's paired with in a label, or more generally in a phrase 🎀 Some preferred variants just make no sense in combination with other characters, so those combinations should not be added into the Zone file (described as "ZV" or zone variants in RFC 3743) 🧚 If desired, it should be possible to define and implement rules that reduce the preferred variant labels to only the plausible ones 🌸 This could be done with some artificial intelligence tools, with feedback from the registrant, or by selecting based on how often something shows up in other texts ✨ To show one possibility, the OCDNL could be required to be TC-only or SC-only, and if there's more than one preferred variant, the OCDNL will be used as the PV instead of the PV the algorithm produces 🦋

To reemphasize, the tables in [LVT-SC] and [LVT-TC] follow the table format and terminology defined in [RFC3743] 🫶 If anyone plans to implement Chinese domain name registrations based on these two tables, or on ones similar to them, they'll need a complete understanding of RFC 3743 to use those tables properly 💖

(part 1 of 2, part 2 is coming soon, don't go anywhere 🧚🌈)

4. Security Considerations ✨

Okay bestie, this one's giving "same drama, different episode" 💅. This doc has the same security considerations as RFC 3743, which is the one that defines the table formats and operations. Like its base doc, a big part of the goal here is cutting down on security problems caused by characters that look alike or mean similar things 👀. This doc won't add any new security issues 🙌. Still, extra registration restrictions like the ones in Section 3 can lowkey shrink those potential problems even more 🔐✨.

5. Acknowledgements 🫶

Huge thanks to these legends for their ideas and for pushing this tough work over the finish line and getting the results out there 👑: WANG YanFeng, Ai-Chin LU, Shian-Shyong TSENG, QIAN HuaLin, and Li-Ming TSENG 💖.

The authors especially want to thank Joe ZHANG and XiaoMing WANG for their outstanding work on SCVT in [LVT-SC] 🌟. Also, a big shoutout to Kenny HUANG, Zheng-Wei LIN, Shi-Xiong TSENG, Lie-Neng WU, Cheng-Wu PAN, Lin-Mei WEI, and Qi-Qing HSU for their effort and contributions editing the TCVT in [LVT-TC] 🦋. These experts brought the basic materials and some seriously crucial suggestions and principles that made both variant tables happen 🧚.

The authors also gratefully acknowledge everyone who commented on and suggested changes to this document, including James SENG and other JET members 🍓💜.

6. References 📚

6.1. Normative References

[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.

6.2. Informative References

[C2C]      Halpern, J. and J. Kerman, "Pitfalls and Complexities of
           Chinese to Chinese Conversion", International Unicode
           Conference (14th) in Boston, March 1999.

[RFC4290]  Klensin, J., "Suggested Practices for Registration of
           Internationalized Domain Names (IDN)", RFC 4290, December
           2005.

Authors' Addresses 🏡

LEE Xiaodong
CNNIC, No.4 South 4th Street, Zhongguancun
Beijing  100080
Phone: +86 10 58813020

EMail: lee@cnnic.cn
URI:   http://www.cnnic.cn


MAO Wei
CNNIC, No.4 South 4th Street, Zhongguancun
Beijing  100080

Phone: +86 10 58813055
EMail: mao@cnnic.cn
URI:   http://www.cnnic.cn


Erin CHEN
TWNIC, 4F-2, No. 9, Sec. 2, Roosevelt Rd.
Taipei  100
Phone: +886 2 23411313

EMail: erin@twnic.net.tw
URI:   http://www.twnic.net.tw


Nai-Wen HSU
TWNIC, 4F-2, No. 9, Sec. 2, Roosevelt Rd.
Taipei  100

Phone: +886 2 23411313
EMail: snw@twnic.net.tw
URI:   http://www.twnic.net.tw


John C KLENSIN
1770 Massachusetts Ave, #322
Cambridge, MA  02140
USA

Phone: +1 617 491 5735
EMail: john+ietf@jck.com

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