Reference LGR for language: Ukrainian (uk) lgr-second-level-ukrainian-language-18may21-en

This document is mechanically formatted from the above XML file for the LGR. It provides additional summary data and explanatory text. The XML file remains the sole normative specification of the LGR.

Date 2021-05-18
LGR Version 2 (Second Level Reference LGR)
Language uk (Ukrainian Language)
Unicode Version 6.3.0

Table of Contents

1 Description

Label Generation Rules for Ukrainian

Overview

This document specifies a reference set of Label Generation Rules for Ukrainian using a limited repertoire as appropriate for a second level domain.

Repertoire

Most references converge on 33 Cyrillic code points. There is some disagreement concerning U+044A (ъ) CYRILLIC SMALL LETTER HARD SIGN and U+0451 (ё) CYRILLIC SMALL LETTER IO. While CLDR considers U+0451 (ё) CYRILLIC SMALL LETTER IO part of the main alphabet, these appear to be used in Russian words or names, not in Ukrainian words and names themselves. Both of these letters are part of the extended repertoire as defined here along with many letters used for Ukrainian. In Russian, the hard sign indicates the non-palatalization of a consonant preceding a morpheme beginning with a iotated vowel; in Ukrainian this function is met by the use of an apostrophe or of U+02BC (ʼ) MODIFIER LETTER APOSTROPHE.

Note that, while U+02BC (ʼ) MODIFIER LETTER APOSTROPHE is protocol valid (PVALID) in IDNA2008; other forms of apostrophes such as U+0027 (') APOSTROPHE or U+2019 (’) RIGHT SINGLE QUOTATION MARK are DISALLOWED. As [RFC6912] points out, in a public zone, many users may read U+02BC (ʼ) as indistinguishable from the regular apostrophe. Therefore, following the principle of conservatism, and in response to a comment made by the IAB during public Comments, the code point U+02BC (ʼ) is not included here.

An IDN table published in the IANA Repository of IDN Practices for Ukrainian by .ua (Ukrainian cctld) in [700] contains many code points beyond what would be used in Ukrainian and even languages used in adjacent areas. Code points not corroborated by any other reference but used for Belarusian, Russian, and Moldovan have been added to the extended repertoire. South Slavic characters are excluded here.

For other IDNA TLD dedicated to Ukrainian: see .укр [YKP] and the IDNA table in [701]. That table shows a repertoire combining Russian and Ukrainian.

In Ukrainian, the acute accent may be used as a stress mark on the vowel of a syllable or to disambiguate between minimal pairs. However, as in Russian, it is restricted to dictionaries and educational materials. See Stress and Disambiguation in [ACUTE].

Excluded code points

Letters documented in some references but not included:

Extended code points

A number of letters not considered essential to writing the core vocabulary of the language are nevertheless in common use. Where they have not been added to the core repertoire, they are flagged as "extended-cp" in the table of code points. A context rule is provided that by default will prohibit labels with extended code points. To support extended single code points or code point sequences, delete the context "extended-cp" from their repertoire definition.

Variants

None.

Note: a study of a possible variant relationship concerning U+0433 (г) CYRILLIC SMALL LETTER GHE and U+0491 (ґ) CYRILLIC SMALL LETTER GHE WITH UPTURN was undertaken in the context of Ukrainian by a Cyrillic case study team in [CYRILLIC-VIP] (page 6, section 3.2). The experts point to some instability concerning the encoding of the GHE WITH UPTURN and the possible confusion between the two code points by non-Ukrainian users. However, in the context of a Ukrainian LGR it does not seem necessary to establish such a variant relationship between these two code points.

Character Classes

This LGR defines no named character classes.

Rules

Common rules:

Actions

Actions included are the default actions for LGRs as well as those needed to invalidate labels with misplaced combining marks and apostrophe modifiers.

Methodology and Contributors

This reference LGR for Ukrainian for the 2nd Level has been developed by Michel Suignard and Asmus Freytag, verified in expert reviews by Michael Everson, Nicholas Ostler, and Wil Tan, and based on multiple open public consultations.

Changes from Version 1

Language tag has been updated.

References

General reference for the language:

Other references cited in this document:

[ACUTE]
Wikipedia, "Acute accent"
https://en.wikipedia.org/wiki/Acute_accent
[CYRILLIC-VIP]
Sozonov, A. et al., “IDN Variant TLDs – Cyrillic Script Issues”. (Marina del Rey, California: ICANN, October 2011).
http://archive.icann.org/en/topics/new-gtlds/cyrillic-vip-issues-report-06oct11-en.pdf.
[HARD-SIGN]
Wikipedia, "Hard sign",
http://en.wikipedia.org/wiki/Hard_sign
[YKP]
U-Regristry.com website (in Ukrainian)
https://namestore.u-registry.com/
[RFC6912]
RFC6912, "Principles for Unicode Code Point Inclusion in Labels in the DNS",
http://www.rfc-base.org/txt/rfc-6912.txt

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. For more details, see the Table of References below.

2 Repertoire

Repertoire Summary

Number of elements in repertoire 44
Number of extended elements 6
Total entries in table 50
Number of code points
for each script
Cyrillic 39
Common 11
Longest code point sequence 1

Repertoire by Code Point

The following table lists the repertoire by code point (or code point sequence). The data in the Script and Name column are extracted from the Unicode character database. Where a comment in the original LGR is equal to the character name, it has been suppressed.

Some code points or sequences listed in the following table are not part of the repertoire itself; they document targets for out-of-repertoire variant mappings or optional code points as indicated. See also the legend provided below the table.

Code
Point		 Glyph Script Name Ref Required Context Part of
Repertoire		 Comment
U+002D - Common HYPHEN-MINUS [0] not: hyphen-minus-disallowed ✔  
U+0030 0 Common DIGIT ZERO [0]   ✔  
U+0031 1 Common DIGIT ONE [0]   ✔  
U+0032 2 Common DIGIT TWO [0]   ✔  
U+0033 3 Common DIGIT THREE [0]   ✔  
U+0034 4 Common DIGIT FOUR [0]   ✔  
U+0035 5 Common DIGIT FIVE [0]   ✔  
U+0036 6 Common DIGIT SIX [0]   ✔  
U+0037 7 Common DIGIT SEVEN [0]   ✔  
U+0038 8 Common DIGIT EIGHT [0]   ✔  
U+0039 9 Common DIGIT NINE [0]   ✔  
U+0430 а Cyrillic CYRILLIC SMALL LETTER A [0], [100], [130], [201], [301], [401], [700], [701]   ✔  
U+0431 б Cyrillic CYRILLIC SMALL LETTER BE [0], [100], [130], [201], [301], [401], [700], [701]   ✔  
U+0432 в Cyrillic CYRILLIC SMALL LETTER VE [0], [100], [130], [201], [301], [401], [700], [701]   ✔  
U+0433 г Cyrillic CYRILLIC SMALL LETTER GHE [0], [100], [130], [201], [301], [401], [700], [701]   ✔  
U+0434 д Cyrillic CYRILLIC SMALL LETTER DE [0], [100], [130], [201], [301], [401], [700], [701]   ✔  
U+0435 е Cyrillic CYRILLIC SMALL LETTER IE [0], [100], [130], [201], [301], [401], [700], [701]   ✔  
U+0436 ж Cyrillic CYRILLIC SMALL LETTER ZHE [0], [100], [130], [201], [301], [401], [700], [701]   ✔  
U+0437 з Cyrillic CYRILLIC SMALL LETTER ZE [0], [100], [130], [201], [301], [401], [700], [701]   ✔  
U+0438 и Cyrillic CYRILLIC SMALL LETTER I [0], [100], [130], [201], [301], [401], [700], [701]   ✔  
U+0439 й Cyrillic CYRILLIC SMALL LETTER SHORT I [0], [100], [130], [201], [301], [401], [700], [701]   ✔  
U+043A к Cyrillic CYRILLIC SMALL LETTER KA [0], [100], [130], [201], [301], [401], [700], [701]   ✔  
U+043B л Cyrillic CYRILLIC SMALL LETTER EL [0], [100], [130], [201], [301], [401], [700], [701]   ✔  
U+043C м Cyrillic CYRILLIC SMALL LETTER EM [0], [100], [130], [201], [301], [401], [700], [701]   ✔  
U+043D н Cyrillic CYRILLIC SMALL LETTER EN [0], [100], [130], [201], [301], [401], [700], [701]   ✔  
U+043E о Cyrillic CYRILLIC SMALL LETTER O [0], [100], [130], [201], [301], [401], [700], [701]   ✔  
U+043F п Cyrillic CYRILLIC SMALL LETTER PE [0], [100], [130], [201], [301], [401], [700], [701]   ✔  
U+0440 р Cyrillic CYRILLIC SMALL LETTER ER [0], [100], [130], [201], [301], [401], [700], [701]   ✔  
U+0441 с Cyrillic CYRILLIC SMALL LETTER ES [0], [100], [130], [201], [301], [401], [700], [701]   ✔  
U+0442 т Cyrillic CYRILLIC SMALL LETTER TE [0], [100], [130], [201], [301], [401], [700], [701]   ✔  
U+0443 у Cyrillic CYRILLIC SMALL LETTER U [0], [100], [130], [201], [301], [401], [700], [701]   ✔  
U+0444 ф Cyrillic CYRILLIC SMALL LETTER EF [0], [100], [130], [201], [301], [401], [700], [701]   ✔  
U+0445 х Cyrillic CYRILLIC SMALL LETTER HA [0], [100], [130], [201], [301], [401], [700], [701]   ✔  
U+0446 ц Cyrillic CYRILLIC SMALL LETTER TSE [0], [100], [130], [201], [301], [401], [700], [701]   ✔  
U+0447 ч Cyrillic CYRILLIC SMALL LETTER CHE [0], [100], [130], [201], [301], [401], [700], [701]   ✔  
U+0448 ш Cyrillic CYRILLIC SMALL LETTER SHA [0], [100], [130], [201], [301], [401], [700], [701]   ✔  
U+0449 щ Cyrillic CYRILLIC SMALL LETTER SHCHA [0], [100], [130], [201], [301], [401], [700], [701]   ✔  
U+044A ъ Cyrillic CYRILLIC SMALL LETTER HARD SIGN [0], [130], [301], [402], [700], [701] extended-cp ◯  
U+044B ы Cyrillic CYRILLIC SMALL LETTER YERU [0], [301], [402], [700], [701] extended-cp ◯  
U+044C ь Cyrillic CYRILLIC SMALL LETTER SOFT SIGN [0], [100], [130], [201], [301], [401], [700], [701]   ✔  
U+044D э Cyrillic CYRILLIC SMALL LETTER E [0], [301], [402], [700], [701] extended-cp ◯  
U+044E ю Cyrillic CYRILLIC SMALL LETTER YU [0], [100], [130], [201], [301], [401], [700], [701]   ✔  
U+044F я Cyrillic CYRILLIC SMALL LETTER YA [0], [100], [130], [201], [301], [401], [700], [701]   ✔  
U+0451 ё Cyrillic CYRILLIC SMALL LETTER IO [0], [301], [402], [700], [701] extended-cp ◯  
U+0454 є Cyrillic CYRILLIC SMALL LETTER UKRAINIAN IE [0], [100], [130], [201], [301], [401], [700], [701]   ✔  
U+0456 і Cyrillic CYRILLIC SMALL LETTER BYELORUSSIAN-UKRAINIAN I [0], [100], [130], [201], [301], [401], [700], [701]   ✔  
U+0457 ї Cyrillic CYRILLIC SMALL LETTER YI [0], [100], [130], [201], [301], [401], [700], [701]   ✔  
U+045E ў Cyrillic CYRILLIC SMALL LETTER SHORT U [0], [700] extended-cp ◯  
U+0491 ґ Cyrillic CYRILLIC SMALL LETTER GHE WITH UPTURN [0], [100], [130], [201], [301], [401], [700], [701]   ✔  
U+04C2 ӂ Cyrillic CYRILLIC SMALL LETTER ZHE WITH BREVE [0], [700] extended-cp ◯  

Legend

Code Point
A code point or code point sequence.
Glyph
The shape displayed depends on the fonts available to your browser.
Script
Shows the script property value from the Unicode Character Database. Combining marks may have the value Inherited and code points used with more than one script may have the value Common.
Name
Shows the character or sequence name from the Unicode Character Database.
Ref
Links to the references associated with the code point or sequence, if any.
Required Context
Link to a rule defining the required context a code point or sequence must satisfy. If prefixed by “not:” identifies a context that must not occur.
Comment
The comment as given in the XML file. However, if the comment for this row consists only of the code point or sequence name, it is suppressed in this view. By convention, comments starting with “=” denote an alias. If present, the symbol ⍟ marks a default item shared among a set of LGRs.
✔ - core repertoire
A check mark in the Part-of-repertoire column indicates a code point is part of the core repertoire.
◯ - extended repertoire
An open circle indicates a code point is part of an optional extended repertoire, which is normally disabled but could be supported by removing the relevant context restriction.

3 Variant Sets

This LGR does not specify any variants.

4 Classes, Rules and Actions

4.1 Character Classes

The following table lists all named and implicit classes with their definition and a list of their members intersected with the current repertoire (for larger classes, this list is elided).

Name Definition Count Members or Ranges Ref Comment
implicit Tag=sc:Cyrl 39 {0430-044F 0451 0454 0456-0457 045E 0491 04C2}   Any character tagged as Cyrillic
implicit Tag=sc:Zyyy 11 {002D 0030-0039}   Any character tagged as Common

Legend

Members or Ranges
Lists the members of the class as code points (xxx) or as ranges of code points (xxx-yyy). Any class too numerous to list in full is elided with "...".
Tag=ttt
A named or implicit class defined by all code points that share the given tag value (ttt).
Implicit
An anonymous class implicitly defined based on tag value and for which there is no named equivalent.

4.2 Whole label evaluation and context rules

The following table lists all named rules defined in the LGR and indicates whether they are used as trigger in an action or as context (when or not-when) for a code point or variant.

Name Regular Expression Used as
Trigger		 Anchor Used as
Context		 Ref Comment
leading-combining-mark (start)[∅=[[∅=\p{gc=Mn}] ∪ [∅=\p{gc=Mc}]]] ✔     [120] RFC5891 restrictions on placement of combining marks
hyphen-minus-disallowed (((start))← ⚓︎)|(⚓︎ →((end)))|(((start)..\u002D)← ⚓︎)   ✔ C [120] RFC5891 restrictions on placement of U+002D (-)
extended-cp (start)(end)     C   code points from the extended range

Legend

Used as Trigger
This rule triggers one of the actions listed below.
Used as Context
This rule defines a required or prohibited context for a code point C or variant V.
Anchor
This rule has a placeholder for the code point for which it is evaluated.
Regular Expression
A regular expression equivalent to the rule, shown in a modified notation as noted:
⚓︎ - context anchor
Placeholder for the actual code point when a context is evaluated. The code point must occur at the position corresponding to the anchor. Rules containing an anchor cannot be used as triggers.
(...)← - look-behind
If present encloses required context preceding the anchor.
→(..) - look-ahead
If present encloses required context following the anchor.
(... | ...) - choice
When there is more than one alternative in a rule, the choices are separated by the alternation operator (...|...).
start or end
(start) matches the start of the label; (end) matches the end of the label.
. - any code point
. matches any code point.
[\p{ }] - property character set
Set of all characters matching a given value for a Unicode property [\p{prop=val}]. Note: uppercase “\P” defines the complement of a property set.
∪, ∩, ∖, ∆ - set operators
Sets may be combined by set operators (∪ = union, ∩ = intersection, ∖ = difference, ∆ = symmetric difference).
∅= - empty set
Indicates that the following set is empty because of the result of set operations, or because none of its elements is part of the repertoire defined here. A rule with a non-optional empty set never matches.
(^$) - empty label
The regex (^$) matches the empty label. Used as a context rule, it always fails to match, thus disallowing the affected code point in any label. By convention, it is used for context rules that disable code points that are not part of the repertoire, yet explicitly listed in the LGR as excluded or for optional future extension.

4.3 Actions

The following table lists the actions that are used to assign dispositions to labels and variant labels based on the specified conditions. The order of actions defines their precedence: the first action triggered by a label is the one defining its disposition.

# Condition Rule / Variant Set   Disposition Ref Comment
1 if label matches leading-combining-mark → invalid   by default, labels with leading combining marks are invalid
2 if any label (catch-all)   → valid   catch all (default action)

Legend

{...} - variant type set
In the “Rule/Variant Set” column, the notation {...} means a set of variant types.

5 Table of References

The following lists the references cited for specific code points, variants, classes, rules or actions in this LGR. For General references refer to the "References" section in the Description.

[0] The Unicode Consortium. The Unicode Standard, Version 6.3.0, (Mountain View, CA: The Unicode Consortium, 2013. ISBN 978-1-936213-08-5)
Any code point cited was originally encoded in Unicode Version 1.1
[3] The Unicode Consortium. The Unicode Standard, Version 6.3.0, (Mountain View, CA: The Unicode Consortium, 2013. ISBN 978-1-936213-08-5)
Any code point cited was originally encoded in Unicode Version 3.0
[100] Internetstiftelsen i Sverige (IIS), Ukrainian
https://github.com/dotse/IDN-ref-tables/blob/master/language-tables/ukrainian-lang-ref-table.txt
[120] RFC5891, Internationalized Domain Names in Applications (IDNA): Protocol
http://tools.ietf.org/html/rfc5891
[130] RFC5992, section 2.7
https://tools.ietf.org/html/rfc5992
[201] Omniglot Ukrainian
http://www.omniglot.com/writing/ukrainian.htm
[301] Everson, Michael, The Alphabets of Europe, Ukrainian
http://evertype.com/alphabets/ukrainian.pdf
[401] The Unicode Consortium, Common Locale Data Repository - CLDR Version 28 (2015-09-16) - Locale Data Summary for Ukrainian [uk]-
http://www.unicode.org/cldr/charts/28/summary/uk.html
Code points cited are from the set of Main Letters
[402] The Unicode Consortium, Common Locale Data Repository - CLDR Version 28 (2015-09-16) - Locale Data Summary for Ukrainian [uk]-
http://www.unicode.org/cldr/charts/28/summary/uk.html
Code points cited are from the set of Auxiliary Letters
[700] Communication Systems Ltd (.ua Ukrain cctld),
http://www.iana.org/domains/idn-tables/tables/ua_cyrl_1.2.txt
[701] Ukrainian Network Information Centre (UANIC) .укр
https://namestore.u-registry.com/Ukrainian_IDN_Table_v3.txt