Lao
Root Zone Label Generation Rules, 4th Edition
Download lgr-4-lao-script-05nov20-en.xml Summary
| Version | 4 — Root Zone LGR for Lao |
|---|---|
| Date | |
| Tag |
und-Laoo (Lao)
|
| Unicode | 6.3.0 |
| Scope | DNS root zone |
| Source file | lgr-4-lao-script-05nov20-en.xml (18.2kb) |
Description
Root Zone Label Generation Rules for the Lao Script
Overview
This file contains Label Generation Rules (LGR) for the Lao script for the Root zone. For more details on this LGR and its development, as well as background on the script, see "Proposal for a Lao Script Root Zone LGR [Proposal-Lao]". This file is one of a set of LGR files that together form an integrated LGR for the DNS Root Zone [RZ-LGR-4]. The format of this file follows [RFC 7940].
Repertoire
In addition to the 51 code points according to Section 5 “Repertoire” in [Proposal-Lao], the sequence 0EB2 0EB0 has been defined to facilitate implementation of WLE rule follows-vafter-context as a context rule. The repertoire only includes code points used by languages that are actively written in the Khmer script. The repertoire is based on [MSR-4], which is a subset of [Unicode 6.3].
As part of the Root Zone, this LGR includes neither digits nor the HYPHEN-MINUS.
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Each code point or range is tagged with the script or scripts that the code point is used with, one or more categories, and one or more references documenting sufficient justification for inclusion in the repertoire; see "References" below.
Variants
According to Section 6, "Variants" in [Proposal-Lao], this LGR defines no variants.
Character Classes
Consonants: In regular syllables, consonants occur in limited combinations. However, arbitrary combinations are used for acronyms. The LGR therefore considers the restriction on syllabic combinations a matter of spelling and does not enforce them. Consonants may be followed by a semi-consonant mark. Some consonants have been given the tag "Cf", which indicates final consonants. See Section 5, "Consonants" in [Proposal-Lao].
Vowels: Vowels are divided into vowel-above, vowel-before, vowel-below and vowel-after so as to enforce some of the syllable structure using context rules. However, many details have been considered spelling issues and, for simplification, are not modeled in this LGR. See Section 5 in [Proposal-Lao].
Semi-consonant: The character U+0EBC LAO SEMIVOWEL SIGN LO follows consonants (see Section 5 in [Proposal-Lao]).
Tone-mark: Any of four tone marks can follow a consonant or vowel-above or vowel-below (see Section 5 in [Proposal-Lao]).
Signs: The character U+0ECC LAO CANCELLATION MARK follows a final consonant (Cf). The character U+0EC6 (ໆ) LAO KO LA is a repetition mark that can only occur up to 3 times at the end of the label (See Section 5 in [Proposal-Lao]).
Whole Label Evaluation (WLE) and Context Rules
Default Whole Label Evaluation Rules and Actions
The LGR includes the set of required default WLE rules and actions applicable to the Root Zone and defined in [MSR-4]. They are marked with ⍟. The default prohibition on leading combining marks is equivalent to ensuring that a label only starts with a consonant or vowel-before.
Lao-specific Rules
Rules provided in the LGR as described in Section 7 of [Proposal-Lao] reasonably restrict labels so that they conform to Lao syllable structure. These constraints are presented exclusively as context rules.
The rules are:
- follows-consonant — A context rule for semi-consonant. See Section 7 in [Proposal-Lao]. (WLE Rule 1)
- precedes-consonant — A context rule for vowel-before. See Section 7 in [Proposal-Lao]. (WLE Rule 2)
- follows-main-consonant — A context rule for vowel-below, and vowel-above. See Section 7 in [Proposal-Lao]. (WLE Rule 3)
- follows-C-tonemark-vabove — A context rule for vowel-after. See Section 7 in [Proposal-Lao]. (WLE Rule 4)
- follows-vbefore-consonant-cluster — A context rule for a vowel-after sequence. It incorporates consonant-cluster. See Section 7 in [Proposal-Lao]. (WLE Rule 5)
- follows-C-vabove-vbelow — A context rule for tone mark. See Section 7 in [Proposal-Lao]. (WLE Rule 6)
- follows-Cf — A context rule for U+0ECC (໌ ) LAO CANCELLATION MARK. See Section 7 in [Proposal-Lao]. (WLE Rule 7)
- repetition-mark-limit — A rule that limits the occurrence of U+0EC6 ( ໆ ) LAO KO LA at the label end. See Section 7 in [Proposal-Lao]. (WLE Rule 8)
No context rules apply to “consonant” code points. For discussion, see Section 5.1, “Consonants” in [Proposal-Lao].
Methodology and Contributors
The Root Zone LGR for the Lao script was developed by the Lao Generation Panel. For methodology and contributors, see Sections 4 and 8 in [Proposal-Lao], as well as [RZ-LGR-4-Overview].
References
The following general references are cited in this document:
- [MSR-4]
- Integration Panel, "Maximal Starting Repertoire — MSR-4 Overview and Rationale", 7 February 2019, https://www.icann.org/en/system/files/files/msr-4-overview-25jan19-en.pdf
- [Proposal-Lao]
- Lao Generation Panel, "Proposal for Lao Script Root Zone LGR", https://www.icann.org/en/system/files/files/proposal-lao-lgr-41jan17-en.pdf
- [RFC 7940]
- Davies, K. and A. Freytag, "Representing Label Generation Rulesets Using XML", RFC 7940, August 2016, http://www.rfc-editor.org/info/rfc7940
- [RZ-LGR-4-Overview]
- Integration Panel, "Root Zone Label Generation Rules - LGR-4: Overview and Summary", 05 November 2020 (PDF), https://www.icann.org/sites/default/files/lgr/lgr-4-overview-05nov20-en.pdf
- [RZ-LGR-4]
- Integration Panel, "Label Generation Rules for the Root Zone — LGR-4", 05 November 2020 (XML), https://www.icann.org/sites/default/files/lgr/lgr-4-common-05nov20-en.xml
non-normative HTML presentation: https://www.icann.org/sites/default/files/lgr/lgr-4-common-05nov20-en.html - [Unicode 6.3]
- The Unicode Consortium. The Unicode Standard, Version 6.3.0, (Mountain View, CA: The Unicode Consortium, 2013. ISBN 978-1-936213-08-5) http://www.unicode.org/versions/Unicode6.3.0/
For references consulted particularly in designing the repertoire for the Lao 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 [201], [202], [203], [204], 205], [206], & [207] correspond to sources given in [Proposal-Lao] justifying the inclusion of or classification for the corresponding code points. Entries in the table may have multiple source reference values.
Repertoire
| Glyph | Code point | Tags and context | Variants |
|---|---|---|---|
| ກ | U+0E81 LAO LETTER KO 0 201 204 Lao |
 Cfconsonantsc:Laoo
|
|
| ຂ | U+0E82 LAO LETTER KHO SUNG 0 201 204 Lao |
consonantsc:Laoo
|
|
| ຄ | U+0E84 LAO LETTER KHO TAM 0 201 204 Lao |
consonantsc:Laoo
|
|
| ງ | U+0E87 LAO LETTER NGO 0 201 204 Lao |
Cfconsonantsc:Laoo
|
|
| ຈ | U+0E88 LAO LETTER CO 0 201 204 Lao |
consonantsc:Laoo
|
|
| ຊ | U+0E8A LAO LETTER SO TAM 0 201 204 Lao |
Cfconsonantsc:Laoo
|
|
| ຍ | U+0E8D LAO LETTER NYO 0 201 204 Lao |
Cfconsonantsc:Laoo
|
|
| ດ | U+0E94 LAO LETTER DO 0 201 204 Lao |
Cfconsonantsc:Laoo
|
|
| ຕ | U+0E95 LAO LETTER TO 0 201 204 Lao |
consonantsc:Laoo
|
|
| ຖ | U+0E96 LAO LETTER THO SUNG 0 201 204 Lao |
consonantsc:Laoo
|
|
| ທ | U+0E97 LAO LETTER THO TAM 0 201 204 Lao |
Cfconsonantsc:Laoo
|
|
| ນ | U+0E99 LAO LETTER NO 0 201 204 Lao |
Cfconsonantsc:Laoo
|
|
| ບ | U+0E9A LAO LETTER BO 0 201 204 Lao |
Cfconsonantsc:Laoo
|
|
| ປ | U+0E9B LAO LETTER PO 0 201 204 Lao |
consonantsc:Laoo
|
|
| ຜ | U+0E9C LAO LETTER PHO SUNG 0 201 204 Lao |
consonantsc:Laoo
|
|
| ຝ | U+0E9D LAO LETTER FO TAM 0 201 204 = lao letter fo sung; Lao |
consonantsc:Laoo
|
|
| ພ | U+0E9E LAO LETTER PHO TAM 0 201 204 Lao |
consonantsc:Laoo
|
|
| ຟ | U+0E9F LAO LETTER FO SUNG 0 201 204 = lao letter fo tam; Lao |
Cfconsonantsc:Laoo
|
|
| ມ | U+0EA1 LAO LETTER MO 0 201 204 Lao |
Cfconsonantsc:Laoo
|
|
| ຢ | U+0EA2 LAO LETTER YO 0 201 204 Lao |
consonantsc:Laoo
|
|
| ຣ | U+0EA3 LAO LETTER LO LING 0 204 = lao letter lo rada; Lao |
Cfconsonantsc:Laoo
|
|
| ລ | U+0EA5 LAO LETTER LO LOOT 0 201 204 = lao letter lo ling; Lao |
Cfconsonantsc:Laoo
|
|
| ວ | U+0EA7 LAO LETTER WO 0 201 204 205 Lao |
Cfconsonantsc:Laoo
|
|
| ສ | U+0EAA LAO LETTER SO SUNG 0 201 204 Lao |
Cfconsonantsc:Laoo
|
|
| ຫ | U+0EAB LAO LETTER HO SUNG 0 201 204 Lao |
consonantsc:Laoo
|
|
| ອ | U+0EAD LAO LETTER O 0 201 204 205 Lao |
consonantsc:Laoo
|
|
| ຮ | U+0EAE LAO LETTER HO TAM 0 201 204 Lao |
consonantsc:Laoo
|
|
| ະ | U+0EB0 LAO VOWEL SIGN A 0 201 205 206 Lao |
sc:Laoovowel-after
 follows-C-tonemark-vabove
|
|
| ັ | U+0EB1 LAO VOWEL SIGN MAI KAN 0 201 205 206 Lao |
sc:Laoovowel-above
follows-main-consonant
|
|
| າ | U+0EB2 LAO VOWEL SIGN AA 0 201 205 206 Lao |
sc:Laoovowel-after
follows-C-tonemark-vabove
|
|
| າະ | U+0EB2U+0EB0 sequence of 2 LAO VOWEL SIGN AA + LAO VOWEL SIGN A 205 Lao |
follows-vbefore-consonant-cluster
|
|
| ິ | U+0EB4 LAO VOWEL SIGN I 0 201 205 206 Lao |
sc:Laoovowel-above
follows-main-consonant
|
|
| ີ | U+0EB5 LAO VOWEL SIGN II 0 201 205 206 Lao |
sc:Laoovowel-above
follows-main-consonant
|
|
| ຶ | U+0EB6 LAO VOWEL SIGN Y 0 201 205 206 Lao |
sc:Laoovowel-above
follows-main-consonant
|
|
| ື | U+0EB7 LAO VOWEL SIGN YY 0 201 205 206 Lao |
sc:Laoovowel-above
follows-main-consonant
|
|
| ຸ | U+0EB8 LAO VOWEL SIGN U 0 201 205 206 Lao |
sc:Laoovowel-below
follows-main-consonant
|
|
| ູ | U+0EB9 LAO VOWEL SIGN UU 0 201 205 206 Lao |
sc:Laoovowel-below
follows-main-consonant
|
|
| ົ | U+0EBB LAO VOWEL SIGN MAI KON 0 205 Lao |
sc:Laoovowel-above
follows-main-consonant
|
|
| ຼ | U+0EBC LAO SEMIVOWEL SIGN LO 0 201 205 206 = lao semiconsonant lo; Lao |
sc:Laoosemi-consonant
follows-consonant
|
|
| ຽ | U+0EBD LAO SEMIVOWEL SIGN NYO 0 201 205 = lao semivowel ia; Lao |
sc:Laoovowel-after
follows-C-tonemark-vabove
|
|
| ເ | U+0EC0 LAO VOWEL SIGN E 0 201 205 206 Lao |
sc:Laoovowel-before
precedes-consonant
|
|
| ແ | U+0EC1 LAO VOWEL SIGN EI 0 201 205 206 Lao |
sc:Laoovowel-before
precedes-consonant
|
|
| ໂ | U+0EC2 LAO VOWEL SIGN O 0 201 205 206 Lao |
sc:Laoovowel-before
precedes-consonant
|
|
| ໃ | U+0EC3 LAO VOWEL SIGN AY 0 201 205 206 Lao |
sc:Laoovowel-before
precedes-consonant
|
|
| ໄ | U+0EC4 LAO VOWEL SIGN AI 0 201 205 206 Lao |
sc:Laoovowel-before
precedes-consonant
|
|
| ໆ | U+0EC6 LAO KO LA 0 203 = lao may sam; Lao |
sc:Laoosign
repetition-mark-limit
|
|
| ່ | U+0EC8 LAO TONE MAI EK 0 202 Lao |
sc:Laootone-mark
follows-C-vabove-vbelow
|
|
| ້ | U+0EC9 LAO TONE MAI THO 0 202 Lao |
sc:Laootone-mark
follows-C-vabove-vbelow
|
|
| ໊ | U+0ECA LAO TONE MAI TI 0 202 Lao |
sc:Laootone-mark
follows-C-vabove-vbelow
|
|
| ໋ | U+0ECB LAO TONE MAI CATAWA 0 202 = lao tone mai jattawa; Lao |
sc:Laootone-mark
follows-C-vabove-vbelow
|
|
| ໌ | U+0ECC LAO CANCELLATION MARK 0 207 = lao mark mai ka lan; Lao |
sc:Laoosign
follows-Cf
|
|
| ໍ | U+0ECD LAO NIGGAHITA 0 201 205 206 = lao vowel sign or; Lao |
sc:Laoovowel-above
follows-main-consonant
|
Character classes
Named sets of code points that the rules below refer to.
| Name | Definition |
|---|---|
Cf |
{tag Cf}
Any Lao final consonant
|
consonant |
{tag consonant}
Any Lao consonant
|
semi-consonant |
{tag semi-consonant}
Lao semi-consonant LO
|
tone-mark |
{tag tone-mark}
Any Lao one mark
|
vowel-above |
{tag vowel-above}
Any Lao vowel above
|
vowel-below |
{tag vowel-below}
Any Lao vowel below
|
Rules
Conditions evaluated against a whole label, or against the context around a
single code point. The notation borrows from regular expressions:
^ and $ anchor to the start and end of a label,
. matches any code point, (?= ) and
(?<= ) look ahead and behind, and * and
+ repeat. Two symbols are specific to rulesets:
◆ is the code point being tested, and
⟨name⟩ refers to another rule.
leading-combining-mark MSR default
Default WLE rule matching labels with leading combining marks
^ ({gc:Mn} ∪ {gc:Mc})
Structure
-
^start -
({gc:Mn} ∪ {gc:Mc})union-
{gc:Mn}class -
{gc:Mc}class
-
Referenced by 1 definition
- action 1 (invalid)
follows-consonant
WLE Rule 1: A semi-consonant must follow a consonant
(?<= {consonant} ) ◆
Structure
-
(?<= {consonant} )look-behind-
{consonant}class
-
-
◆anchor
Referenced by 1 definition
- context of U+0EBC
precedes-consonant
WLE Rule 2: A vowel-before precedes a main consonant cluster
◆ (?= {consonant} )
Structure
-
◆anchor -
(?= {consonant} )look-ahead-
{consonant}class
-
Referenced by 5 definitions
- context of U+0EC0
- context of U+0EC1
- context of U+0EC2
- context of U+0EC3
- context of U+0EC4
follows-main-consonant
WLE Rule 3: A vowel-above, and vowel-below follow a main consonant C
(?<= ( {consonant} │ {semi-consonant} ) ) ◆
Structure
-
(?<= ( {consonant} │ {semi-consonant} ) )look-behind-
( {consonant} │ {semi-consonant} )choice-
{consonant}class -
{semi-consonant}class
-
-
-
◆anchor
Referenced by 9 definitions
- context of U+0EB1
- context of U+0EB4
- context of U+0EB5
- context of U+0EB6
- context of U+0EB7
- context of U+0EB8
- context of U+0EB9
- context of U+0EBB
- context of U+0ECD
follows-C-tonemark-vabove
WLE Rule 4: A vowel-after follows a main consonant, tone-mark or vowel-above
(?<= ( {consonant} │ {semi-consonant} │ {tone-mark} │ {vowel-above} ) ) ◆
Structure
-
(?<= ( {consonant} │ {semi-consonant} │ {tone-mark} │ {vowel-above} ) )look-behind-
( {consonant} │ {semi-consonant} │ {tone-mark} │ {vowel-above} )choice-
{consonant}class -
{semi-consonant}class -
{tone-mark}class -
{vowel-above}class
-
-
-
◆anchor
Referenced by 3 definitions
- context of U+0EB0
- context of U+0EB2
- context of U+0EBD
consonant-cluster
Defining consonant cluster for WLE Rule 5
{consonant}{1:2} {semi-consonant}{0:1}
Referenced by 1 definition
- rule follows-vbefore-consonant-cluster
follows-vbefore-consonant-cluster
WLE Rule 5: The sequence U+0EB2 U+0EB0 follows a vowel before, and a consonant cluster
(?<= U+0EC0 ⟨consonant-cluster⟩ ) ◆
Structure
-
(?<= U+0EC0 ⟨consonant-cluster⟩ )look-behind-
U+0EC0char -
⟨consonant-cluster⟩rule
-
-
◆anchor
Referenced by 1 definition
- context of U+0EB2 U+0EB0
follows-C-vabove-vbelow
WLE Rule 6: A tone-mark follows a main consonant, vowel-above or vowel-below
(?<= ( {consonant} │ {semi-consonant} │ {vowel-above} │ {vowel-below} ) ) ◆
Structure
-
(?<= ( {consonant} │ {semi-consonant} │ {vowel-above} │ {vowel-below} ) )look-behind-
( {consonant} │ {semi-consonant} │ {vowel-above} │ {vowel-below} )choice-
{consonant}class -
{semi-consonant}class -
{vowel-above}class -
{vowel-below}class
-
-
-
◆anchor
Referenced by 4 definitions
- context of U+0EC8
- context of U+0EC9
- context of U+0ECA
- context of U+0ECB
follows-Cf
WLE Rule 7: The sign U+0ECC can only occur after final consonants
(?<= {Cf} ) ◆
Structure
-
(?<= {Cf} )look-behind-
{Cf}class
-
-
◆anchor
Referenced by 1 definition
- context of U+0ECC
repetition-mark-limit
WLE Rule 8: The sign U+0EC6 can only occur 0 to 3 times at the end of the label
◆ (?= U+0EC6{0:2} $ )
Structure
-
◆anchor -
(?= U+0EC6{0:2} $ )look-ahead-
U+0EC6{0:2}char -
$end
-
Referenced by 1 definition
- context of U+0EC6
Actions
Actions are evaluated in the order shown. The first action whose conditions match determines the disposition of the label.
| # | Disposition | Conditions |
|---|---|---|
| 1 |
invalid
|
label matches leading-combining-mark labels with leading combining marks are invalid MSR default |
| 2 |
invalid
|
any variant is out-of-repertoire-var any variant label with a code point out of repertoire is invalid MSR default |
| 3 |
blocked
|
any variant is blocked any variant label containing blocked variants is blocked MSR default |
| 4 |
allocatable
|
all variants are allocatable variant labels with all variants allocatable are allocatable MSR default |
| 5 |
valid
|
any label default catch all (default action) MSR default |
References
| Ref | Source |
|---|---|
| 0 | The Unicode Standard 1.1 |
| 201 | Lao grammar book published by the Ministry of Education in 1967, see Appendix B, Figure 1 in [Proposal-Lao] |
| 202 | Lao grammar book published by the Ministry of Education in 1967, see Appendix B, Figure 2 in [Proposal-Lao] |
| 203 | Lao grammar book published by the Ministry of Education in 1967, see Appendix B, Figure 3 in [Proposal-Lao] |
| 204 | Lao grammar book published by the Ministry of Education in 2000, see Appendix B, Figure 4 in [Proposal-Lao] |
| 205 | Lao grammar book published by the Ministry of Education in 2000, see Appendix B, Figure 5 in [Proposal-Lao] |
| 206 | Lao grammar book published by the Ministry of Education in 2000, see Appendix B, Figure 6 in [Proposal-Lao] |
| 207 | Lao grammar 1935, see Appendix B, Figure 7 in [Proposal-Lao] |