This file contains a set of Label Generation Rules (LGR) for the Japanese script for the Root Zone. For more details on this LGR and additional background on the script, see “Proposal for a Japanese Script Root Zone LGR” [Proposal-Japanese], including the appendices [Proposal-Japanese-Appendices]. The Repertoire for the Japanese script combines elements from three Unicode scripts: Han (Kanji), Hiragana and Katakana. This file is one of a set of LGR files that together form an integrated LGR for the DNS Root Zone [RZ-LGR-6]. The format of this file follows [RFC 7940].
The repertoire includes 6,356 Han characters, 85 Hiragana characters, 89 Katakana characters, and 2 Common (quasi-Kanji) characters for a total of 6,532 repertoire elements. One of the common characters is shared between Han, Hiragana, and Katakana, while the other one is shared between Hiragana and Katakana. For more details, see Section 5, “Repertoire” in [Proposal-Japanese].
The repertoire contains code points used in writing the Japanese language using a limited repertoire as would be appropriate for the Root Zone. Each code point in the repertoire is part of JIS X 0208:1997 [100], which is also the basis for Japanese IDNs on the second level.
The repertoire is contained in [MSR-6], which is a subset of [Unicode 16.0.0].
As part of the Root Zone, this LGR includes neither decimal digits nor the HYPHEN-MINUS.
Repertoire Listing: Each code point or range is tagged with the script or scripts with which the code point is used. For each repertoire element, one or more references document sufficient justification for inclusion in the repertoire; see the “References” below.
This LGR defines no named character classes.
According to Sections 6 and 7 of [Proposal-Japanese] the LGR defines visually identical variants within the Japanese script.
Additional Variants: This LGR inherits additional blocked cross-script variants by integration; they may not be listed here unless they result in in-script variants. See the merged, Common LGR [RZ-LGR-6] for details of all applicable cross-script variants, including any not listed here; always use the Common LGR for determining cross-script collisions of labels. For example, this LGR includes all in-script variants acquired through integration with the Chinese RZ-LGR [CLGR] and Korean RZ-LGR [KLGR].
Variant Disposition: All variants are of type “blocked”, making labels that differ only by these variants mutually exclusive: whichever label containing either of these variants is chosen earlier would be delegated, while any other equivalent labels should be blocked. There is no preference among these labels.
This LGR does not define allocatable variants.
The specification of variants in the Root Zone LGR follows the guidelines in [RFC 8228].
The following source references are used for variant entries in this LGR:
The LGR includes the set of required default WLE rules and actions applicable to the Root Zone and defined in [MSR-6]. They are marked with ⍟. The actions compute a label disposition based on WLE rules or variant mapping types.
As described in Section 8 in [Proposal-Japanese], the Japanese LGR defines a single context rule for marks that cannot start a label.
Iteration marks: The iteration marks, U+309D, U+309E, U+30FD, and U+30FE, are used to reiterate the pronunciation the preceding character, while the U+3005 IDEOGRAPHIC ITERATION MARK repeats the meaning of the preceding character. As such, these characters have neither particular pronunciation nor meanings by themselves. They also should not be applied to a closing mark U+3006, except that U+3005 IDEOGRAPHIC ITERATION MARK may follow U+3006 IDEOGRAPHIC CLOSING MARK in the popular combination 〆々 "shimeshime".
Similar considerations apply to U+30FC KATAKANA-HIRAGANA PROLONGED SOUND MARK. Accordingly, any sequence consisting of any combination of two or more iteration marks and/or the prolonged sound mark has no meaning and is disallowed by the following WLE rule and corresponding action:
The Root Zone LGR for the Japanese Script was developed by the Japanese Generation Panel. For details on methodology and contributors, see Sections 4 and 9 in [Proposal-Japanese], as well as [RZ-LGR-6-Overview].
A WLE rule and action were added in RZ LGR-6 to ensure that iteration marks and the prolonged sound mark are not repeated and do not follow U+3006. This may affect the validity of labels if they erroneously contain more than one of these symbols in an invalid combination. For the prior version see [RZ-LGR-5-Jpan].
References [0] and up refer to the Unicode Standard versions in which corresponding code points were initially encoded. For example, a reference value of [0] means a character was first encoded in Unicode Version 1.1. References [100] and up indicate that the code point is included in one of the following source references: JIS X 0208:1997, Survey on the user perception of the homographic character set specified by JGP, CLGR repertoire, and KLGR repertoire. For example, a reference value of [300] means a code point listed here is included in the CLGR repertoire. References cited for variants indicate whether variant mappings match a source reference in mapping, variant type or both. Entries in the table may have multiple source reference values.
In addition, the following general references are cited in this document:
For references consulted, particularly in designing the repertoire for the Japanese script for the Root Zone, please see details in the Table of References below. Reference [0] refers to the Unicode Standard version in which corresponding code points were initially encoded. References [100] and above corresponds to a source given in [Proposal-Japanese] for justifying the inclusion of the corresponding code points and variants. Entries in the table may have multiple source reference values. If links to certain references are not available, the data may be archived as part of [Proposal-Japanese].
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