This document specifies a set of Label Generation Rules (LGR) for the Chinese language for the second level domain or domains identified above. The ultimate starting point for the development of this LGR can be found in the related Root Zone LGR [RZ-LGR-Hani]. Note that while it is the Chinese Script Root Zone LGR that forms the starting point, the LGR defined here covers the Chinese Language. The format of this file follows [RFC 7940]. This LGR is adapted from the “Reference LGR for the Second Level for the Chinese Language” [Ref-LGR-zh-Hani], for details, see Change History below.
For details and additional background on the Chinese script, see “Proposal for a Chinese Script Root Zone LGR” [Proposal-Chinese] including the appendices [Proposal-Chinese-Appendices].
Standalone LGR: This LGR is designed to be used in a zone that does not cater to IDNs other than those valid under this LGR. Following existing practice, this LGR also supports ASCII letters and where applicable accounts for any interaction with the remainder of the repertoire.
The repertoire contains 19,685 code points for Han ideographs. This set is the union of the Han ideographs for CDNC IDN Table 2.0/2018 and the dotAsia IDN Table. The repertoire is a subset of [Unicode 11.0.0]. For details, see Section 5, “Repertoire” in [Proposal-Chinese]. (The proposal cited has been adopted for the Chinese script portion of the Root Zone LGR.)
Note: This LGR contains 62 code points from the Unicode block: CJK UNIFIED IDEOGRAPHS EXTENDED B.
For the second level, the repertoire has been augmented with the ASCII digits, U+0030 to U+0039; the ASCII lowercase letters, U+0061 to U+007A; and U+002D HYPHEN-MINUS, for a total of 19,722 repertoire elements.
Unlike many other non-Latin Second Level Reference LGRs, the Chinese Language LGR includes the basic ASCII Latin letters (a to z) because it is common practice in Chinese text to mix Chinese and ASCII. Therefore including these letters is not seen as creating added confusability or security risks in the context of a Second Level LGR for the Chinese language. It is also supported by current IDNA practice, see [200], for example.
Any code points outside the Chinese Language repertoire that are targets for out-of-repertoire variants would be included here only if the variant is listed in this file. In this case they are identified as a reflexive (identity) variant of type “out-of-repertoire-var”. Whether or not they are listed, they do not form part of the repertoire.
Repertoire Listing: Each code point or range is tagged with the script or scripts with which the code point is used and one or more other character categories. For each repertoire element, one or more references document sufficient justification for inclusion in the repertoire; see the “References” below.
The variants defined in this LGR are limited to those required for use in zones not shared with any other language. As such, this LGR does not define cross-language variants. However, using this LGR concurrently with any LGR for Japanese and Korean in the same zone will introduce some in-script variants due to cross-script variant transitivity. This will also create potential cross-script issues when used with the same LGRs. For details, see Section 6, “Variants” in [Proposal-Chinese]. Mitigation of these in-script and cross-script variants can be addressed by using the Common LGR. For details, see Section 3, “Use of Multiple Reference LGRs in the Same Zone” in [Level-2-Overview]. In addition to variants defined by this LGR, the full variant information related to this script and added by concurrent use with the Japanese and Korean LGR(s) can be found in the following LGR: [Ref-LGR-Chinese-Full-Variant-Script]
This LGR defines both semantically interchangeable variants (same pronunciations as well as the same meanings) and visually identical variants. Many, but not all, of the semantic variants lead to variant label dispositions of “allocatable” as described below, all other variant labels are “blocked”. For details, see Sections 6 and 7 of [Proposal-Chinese].
The source reference cited for each variant mapping entry indicates whether the variant mapping is same or different from the rules of CDNC, dotAsia, JGP and KGP, or is based on input during the Root Zone LGR integration process.
For example, a value of “201” means the variant mapping matches dotAsia in both code point and variant type, a value of “202” means the variant mapping matches dotAsia only in code point but not variant type, while a value of “203” means the variant mapping matches no dotAsia code point.
A value of “701” means the variant mapping agrees with input received during the Root Zone integration process in both code point and variant type.
Where variants exist between the Chinese, Japanese and Korean scripts, out-of-repertoire variants may be defined with an out-of-repertoire-var mapping type. As result of integration, including the effects of cross-script transitivity, the number of cross-script variants listed for these scripts may be larger than defined in Section 6, “Variants” in [Proposal-Chinese].
When integrated to be used with another script LGR in the same zone, this LGR may inherit additional blocked cross-script variants by integration; they may not be listed here unless they reflect resulting in-script variants. Always use an applicable merged, or Common LGR created by integration for determining cross-script collisions of labels. However, the list of in-repertoire variants in this LGR is exhaustive.
The LGR uses the following variant types (the prefix “r-” here marks a type used in a reflexive variant mapping, that is, it represents an instance of the original code point at that location, see Section 5.3.4 in [RFC 7940]):
The variant types (“simp-1”, “simp-2”, “trad-1”, “trad-2”) and the corresponding actions reduce the number of multiple allocatable labels, limiting the number to no more than 5 per label. This case can occur for labels containing code points that are part of a small number of variant sets that have multiple traditional or simplified variants.
Note that a label containing only reflexive mappings, including “r-neither”, but not “out-of-repertoire-var” is an original label and receives a disposition of “valid”. (See also “Chinese-specific Actions” below.)
The LGR does not define specific variant types to handle visually identical variants, but adopts “both” and “blocked” instead, as described in Section 7 of [Proposal-Chinese].
As much as possible the scheme retains the same simplified and traditional mappings as existing second level domains. It does not change the simplified type or traditional type of any variant code point; instead, it subdivides them into common simplified/traditional ones and extra simplified/traditional ones, and provides additional disposition rules to limit any allocatable variant to one of these subgroups. While it does not allow the applicant to get arbitrary mixed labels from an unconstrained allocatable label list, it does allow the applicant to select as the original label one specific desired mixed variant.
The comment for each variant mapping entry indicates not only whether it is the reflexive identity and therefore applies to those code points in a label that match the original label, but also documents whether it has been conflated with some other type originally introduced to reduce the number of multiple allocatable labels in Section 6.3.3 of [Proposal-Chinese].
For example, a variant comment of “r-both-ms” indicates that for a given code point, the variant is a code point that could in principle be used with both trad and simp (“r-both”), but because the same variant set has at least one other variant of type “simp” (or of one of the other simplified types), the variant is preferred in a traditional context, such that a “trad” label containing this variant should be “allocatable”, but a “simp” label containing this variant should be “blocked”. The “ms” in the naming convention means that the simplified aspect of the variant is “muted”, even though inherently if would have been of type “r-both”. Effectively, such a variant leads to the same dispositions as an “r-trad”, hence that is the variant type assigned to it, with only the comment indicating that the variant would have inherently been of type “r-both” but with its simp aspect muted.
This LGR does not define named character classes.
By default, the LGR includes the rules and actions to implement the following restrictions mandated by the IDNA protocol. They are marked with ⍟.
None.
The LGR defines a number of actions that compute a label disposition based on WLE rules or variant mapping types. Some of these are common to all LGRs, and some are specific to this LGR.
This LGR includes the default actions for LGRs as well as the action needed to invalidate labels with misplaced combining marks. They are marked with ⍟. For a description see [RFC 7940].
The LGR contains additional Chinese-specific actions as described in Sections 6 and 7 of [Proposal-Chinese]. These resolve the extended set of variant types into a disposition for variant labels of either “allocatable”, “blocked” (or “valid” for an original label that is the identity variant). Chinese-specific actions that are triggered by the LGR-specific variant types described above limit the “allocatable” variant labels to those that are either fully simplified or fully traditional labels. In addition, these actions return a disposition of “valid” for any original label, even those that are mixed between simplified and traditional (see also [RFC 3743] and [RFC 4713]). To account for original labels, reflexive variant mappings with an “r-” prefix are used. (See [RFC 7940])
Note: the only action explicitly triggered by variant type sets including variant type “r-neither” returns a disposition of “valid” for an original label.
Note that variant mapping types are not symmetric: they depend on which code point is considered the source or the target in a given mapping. As specified in [RFC 7940], mapping types are evaluated for each permutation of a label and its variants, with code points that are unchanged in a given label given the type of their “reflexive” or “identity” mapping. The actions finally evaluate the collected set of mapping types and resolve them into one of two dispositions for the variant label. Per [RFC 7940] actions are always applied one after the other, and the evaluation stops at the first action that assigns a disposition to a given label.
For more information on how to assign a variant label disposition under this LGR, see Section 8, “Assigning Variant Dispositions to Labels” in [Proposal-Chinese].
The specification of variants in this LGR follows the guidelines in [RFC 8228].
The LGR in this document has been adapted from the corresponding Reference LGR for the Second Level. The Second Level Reference LGR for the Chinese Language was developed by Michel Suignard and Asmus Freytag, based on the Root Zone LGR for the Chinese script and information contained or referenced therein; see [RZ-LGR-Hani]. Suitable extensions for the second level have been applied according to the [Guidelines] and with community input. As part of that process, features have been removed or modified as appropriate for the target language. The original proposal for a Root Zone LGR for the Chinese script, that this LGR is based on, was developed by the Chinese Generation Panel. For more information on methodology and contributors to the underlying Root Zone LGR, see Sections 4 and 9 in [Proposal-Chinese], as well as [RZ-LGR-Overview].
For consistency, the disposition for labels consisting of only original code points is now “valid” instead of “allocatable”. With this change, original labels are now either valid or invalid, whereas any variant labels are either allocatable or blocked. This removes an exception in processing original labels without affecting the set of labels available for delegation.
Unicode Version has been updated.
Description better aligned with [RZ-LGR-Hani] description.
This version modifies the Second Level Reference LGR for the Chinese Language [Ref-LGR-zh-Hani] by injecting the complete (maximal) set of cross-repertoire variants, including any imposed by transitivity. Injected variants are marked by special comments. Any character classes, context and WLE rules required for testing are also imported. In all other respects, description or annotations have not been updated to reflect the injected variants. Any LGR elements that might pose a possible conflict when the LGR is used with the Common LGR for cross-repertoire variant resolution are clearly marked. All modifications are carried out mechanically; there may be an occasional context rule or similar that is injected because its definition relates to some repertoire element even though it can never be triggered by any label valid under the modified LGR.
References [0] to [4] refer to the Unicode Standard versions in which corresponding code points were initially encoded. References [100], [200], [300], [400], [500], and [600] correspond to sources given in [Proposal-Chinese] for justifying the inclusion of for the corresponding code points. References [101], [102], [103], [201], [202], [203], [301], [501], and [701] correspond to variant mapping types given in [Proposal-Chinese] for justifying these mapping types. Entries in the table may have multiple source reference values. In the listing of whole label evaluation and context rules, reference [150] indicates the source for common rules.
In addition, the following general references are cited in this document:
In the listing of the repertoire by code point, references starting from [0] refer to the version of the Unicode Standard in which the corresponding code point was initially encoded. Other references (starting from [100]) document usage of code points. Entries in the table may have multiple source reference values. In the listing of whole label evaluation and context rules, reference [150] indicates the source for common rules. For more details, see the Table of References below.
Where stable links to certain references are not publicly available, the data may be archived in [Proposal-Chinese-Appendices].
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