| Root Zone LGR for script: Thai (Thai) | rz-lgr-6-thai-script-23sep25-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 | 2025-09-23 |
|---|---|
| LGR Version | 6 (Root Zone LGR for the Thai Script) |
| Language | und-Thai (Thai Script) |
| Scope | domain: "." (Root) |
| Unicode Version | 16.0.0 |
Description
Root Zone Label Generation Rules for the Thai Script
Overview
This file contains a set of Label Generation Rules (LGR) for the Thai script for the Root Zone. For more details on this LGR and additional background on the script, see “Proposal for the Thai Script Root Zone LGR” [Proposal-Thai]. 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].
Repertoire
In addition to the 68 single code points according to Section 5 “Repertoire” in [Proposal-Thai], three sequences have been defined, for a total of 71 repertoire elements. The sequence U+0E4D U+0E32 ํา was defined to replace the disallowed U+0E33 (SARA AM) and to facilitate implementation of WLE rule follows-consonant-tone as a context rule. The other two sequences were defined to restrict U+0E45 (LAKKHANGYAO) from appearing in any context other than these sequences. Accordingly, while U+0E45 ๅ is not listed as a repertoire element by itself it brings the total of distinct code points to 69.
The repertoire only includes code points used by languages that are actively written in the Thai script.
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 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. For code points that are part of the repertoire, comments identify the language using the code point, as well as alternate names of some code points.
Variants
According to Section 6, “Variants” in [Proposal-Thai], this LGR defines no variants.
Character Classes
The Thai Script is an abugida in which consonant–vowel sequences are written as a unit: each unit is based on a consonant letter, and vowel, tone mark or diacritic notation are secondary. It is written with the combining marks stacked above or below the base consonant, like diacritics in European languages. However, although the concepts are quite similar, the implementations are significantly different.
Consonants: There are 44 characters that are classified as consonants; code points from this subset have been given the tag “cons”. See Section 5.1, “Consonants” in [Proposal-Thai].
Vowels: The 18 vowel symbols pronounced after a consonant are non-sequential: they can be located before (lv) , after (fv), above (av) or below (bv) the consonant, or in a combination of these positions, code points from this subset have been given the tags “fv1”, “fv2”, “fv3”, “av”, “bv”, or “lv”. There are three code point sequences defined that include vowels. (Code point sequences do not carry tag values; instead, for code point sequences the subset values are identified in comments). See Section 5.2, “Vowels” in [Proposal-Thai].
Tones: There are 5 phonemic tones: mid, low, falling, high, and rising. These 5 tones are represented by 4 tone marks plus the absence of a mark. Code points from this subset have been given the tag “tone”. See section 5.3, “Tone Marks” in [Proposal-Thai].
Diacritical Marks: There are 3 diacritic symbols above that have been included here and given the tag “ad”. They differ in their frequency and purpose of usage. See also the discussion in Section 5.4, “Diacritics” in [Proposal-Thai].
- U+0E47 (MAITAIKHU) and U+0E4C (THANTHAKHAT) are commonly used for words in everyday communication
- U+0E4D (NIKHAHIT) is included because of its use to decompose U+0E33 ( ําา ) THAI CHARACTER SARA AM, which is in common use. However, NIKHAHIT may also be used by itself.
A fourth above diacritic, U+0E4E (YAMAKKAN), has been excluded from the Root Zone LGR repertoire because it is rarely used in Modern Thai or even in older Pali manuscripts; it is more common to replace it with U+0E3A (PHINTHU), a below diacritic, which has been given the tag “bd”. Moreover, excluding U+0E4E (YAMAKKAN) also eliminates the chance of confusion between U+0E4E (YAMAKKAN) and U+0E4C (THANTHAKHAT). Both look similar, are always placed at the same position in the word cell, and they are normally displayed in a small size.
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-6]. They are marked with ⍟. The actions compute a label disposition based on WLE rules or variant mapping types.
Thai-specific Rules
The rules provided in this LGR as described in Section 7 of [Proposal-Thai] reasonably restrict labels so that they conform to Thai syllable structure. These constraints are exclusively presented as context rules.
The rules are:
- A leading-vowel must precede a consonant — See Section 7.2 in [Proposal-Thai]
- A below-vowel must follow a consonant — See Section 7.3 in [Proposal-Thai]
- An above-vowel must follow a consonant — See Section 7.3 in [Proposal-Thai]
- A below diacritic must follow a consonant — See Section 7.3 in [Proposal-Thai]
- An above-diacritic MAITAIKHU must follow a consonant — See Section 7.3 in [Proposal-Thai]
- A vowel MAIHAN AKAT must be in between a consonant and either tone or consonant — See Section 7.4 in [Proposal-Thai]
- A vowel SARA A can follow a consonant, a tone or a vowel SARA AA — See Section 7.5 in [Proposal-Thai]
- A vowel SARA AA, or an above diacritic NIKHAHIT followed by a vowel SARA AA can follow a consonant or a tone — See Sections 7.6 and 7.9 in [Proposal-Thai]
- A tone-mark, THANTHAKHAT, NIKHAHIT can only follow a consonant, above-vowel or below-vowel — See section 7.7 and 7.8 in [Proposal-Thai]
Methodology and Contributors
The Root Zone LGR for the Thai Script was developed by the Thai Generation Panel. For details on methodology and contributors, see Sections 4 and 8 in [Proposal-Thai], as well as [RZ-LGR-6-Overview].
References
The following general references are cited in this document:
- [MSR-6]
- Integration Panel, “Maximal Starting Repertoire — MSR-6 Overview and Rationale”, 23 September 2025,
https://www.icann.org/en/system/files/files/msr-6-overview-23sep25-en.pdf - [Proposal-Thai]
- Thai Generation Panel, “Proposal for the Thai Script Root Zone LGR”, 25 May 2017,
https://www.icann.org/en/system/files/files/proposal-thai-lgr-25may17-en.pdf - [RFC 7940]
- Davies, K. and A. Freytag, “Representing Label Generation Rulesets Using XML”,
RFC 7940, August 2016,
https://www.rfc-editor.org/info/rfc7940 - [RZ-LGR-6-Overview]
- Integration Panel, “Root Zone Label Generation Rules (RZ LGR-6): Overview and Summary”, 23 September 2025,
https://www.icann.org/sites/default/files/lgr/rz-lgr-6-overview-23sep25-en.pdf - [RZ-LGR-6]
- Integration Panel, “Root Zone Label Generation Rules (RZ-LGR-6)”, 23 September 2025 (XML),
https://www.icann.org/sites/default/files/lgr/rz-lgr-6-common-23sep25-en.xml
non-normative HTML presentation:
https://www.icann.org/sites/default/files/lgr/rz-lgr-6-common-23sep25-en.html - [Unicode 16.0.0]
-
The Unicode Consortium. The Unicode Standard, Version 16.0.0, (South San Francisco: The Unicode Consortium, 2024. ISBN 978-1-936213-34-4)
https://www.unicode.org/versions/Unicode16.0.0/
For references consulted, particularly in designing the repertoire for the Thai script for the Root Zone, please see details in the Table of References below. Reference [0] refers to the Unicode Standard version in which the corresponding code points were initially encoded. References [100] and [101] correspond to sources given in [Proposal-Thai] for justifying the inclusion of for the corresponding code points. Entries in the table may have multiple source reference values.
Repertoire
Repertoire Summary
| Number of elements in repertoire | 71 |
|---|---|
| Number of code points | 68 |
| Number of sequences | 3 |
| Longest code point sequence | 2 |
| Code points defined via 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 that may be part of a valid label under this LGR only occur as part of one or more sequences. Such code points are not listed individually in the table.
See also the legend provided below the table.
| Code Point |
Glyph | Script | Name | Ref | Tags | Required Context | Comment |
|---|---|---|---|---|---|---|---|
| U+0E01 | ก | Thai | THAI CHARACTER KO KAI | [0], [100], [101] | cons | Thai | |
| U+0E02 | ข | Thai | THAI CHARACTER KHO KHAI | [0], [100], [101] | cons | Thai | |
| U+0E03 | ฃ | Thai | THAI CHARACTER KHO KHUAT | [0], [100], [101] | cons | Thai | |
| U+0E04 | ค | Thai | THAI CHARACTER KHO KHWAI | [0], [100], [101] | cons | Thai | |
| U+0E05 | ฅ | Thai | THAI CHARACTER KHO KHON | [0], [100], [101] | cons | Thai | |
| U+0E06 | ฆ | Thai | THAI CHARACTER KHO RAKHANG | [0], [100], [101] | cons | Thai | |
| U+0E07 | ง | Thai | THAI CHARACTER NGO NGU | [0], [100], [101] | cons | Thai | |
| U+0E08 | จ | Thai | THAI CHARACTER CHO CHAN | [0], [100], [101] | cons | Thai | |
| U+0E09 | ฉ | Thai | THAI CHARACTER CHO CHING | [0], [100], [101] | cons | Thai | |
| U+0E0A | ช | Thai | THAI CHARACTER CHO CHANG | [0], [100], [101] | cons | Thai | |
| U+0E0B | ซ | Thai | THAI CHARACTER SO SO | [0], [100], [101] | cons | Thai | |
| U+0E0C | ฌ | Thai | THAI CHARACTER CHO CHOE | [0], [100], [101] | cons | Thai | |
| U+0E0D | ญ | Thai | THAI CHARACTER YO YING | [0], [100], [101] | cons | Thai | |
| U+0E0E | ฎ | Thai | THAI CHARACTER DO CHADA | [0], [100], [101] | cons | Thai | |
| U+0E0F | ฏ | Thai | THAI CHARACTER TO PATAK | [0], [100], [101] | cons | Thai | |
| U+0E10 | ฐ | Thai | THAI CHARACTER THO THAN | [0], [100], [101] | cons | Thai | |
| U+0E11 | ฑ | Thai | THAI CHARACTER THO NANGMONTHO | [0], [100], [101] | cons | Thai | |
| U+0E12 | ฒ | Thai | THAI CHARACTER THO PHUTHAO | [0], [100], [101] | cons | Thai | |
| U+0E13 | ณ | Thai | THAI CHARACTER NO NEN | [0], [100], [101] | cons | Thai | |
| U+0E14 | ด | Thai | THAI CHARACTER DO DEK | [0], [100], [101] | cons | Thai | |
| U+0E15 | ต | Thai | THAI CHARACTER TO TAO | [0], [100], [101] | cons | Thai | |
| U+0E16 | ถ | Thai | THAI CHARACTER THO THUNG | [0], [100], [101] | cons | Thai | |
| U+0E17 | ท | Thai | THAI CHARACTER THO THAHAN | [0], [100], [101] | cons | Thai | |
| U+0E18 | ธ | Thai | THAI CHARACTER THO THONG | [0], [100], [101] | cons | Thai | |
| U+0E19 | น | Thai | THAI CHARACTER NO NU | [0], [100], [101] | cons | Thai | |
| U+0E1A | บ | Thai | THAI CHARACTER BO BAIMAI | [0], [100], [101] | cons | Thai | |
| U+0E1B | ป | Thai | THAI CHARACTER PO PLA | [0], [100], [101] | cons | Thai | |
| U+0E1C | ผ | Thai | THAI CHARACTER PHO PHUNG | [0], [100], [101] | cons | Thai | |
| U+0E1D | ฝ | Thai | THAI CHARACTER FO FA | [0], [100], [101] | cons | Thai | |
| U+0E1E | พ | Thai | THAI CHARACTER PHO PHAN | [0], [100], [101] | cons | Thai | |
| U+0E1F | ฟ | Thai | THAI CHARACTER FO FAN | [0], [100], [101] | cons | Thai | |
| U+0E20 | ภ | Thai | THAI CHARACTER PHO SAMPHAO | [0], [100], [101] | cons | Thai | |
| U+0E21 | ม | Thai | THAI CHARACTER MO MA | [0], [100], [101] | cons | Thai | |
| U+0E22 | ย | Thai | THAI CHARACTER YO YAK | [0], [100], [101] | cons | Thai | |
| U+0E23 | ร | Thai | THAI CHARACTER RO RUA | [0], [100], [101] | cons | Thai | |
| U+0E24 | ฤ | Thai | THAI CHARACTER RU | [0], [100], [101] | fv3 | Thai | |
| U+0E24 U+0E45 | ฤๅ | {Thai} | THAI CHARACTER RU + THAI CHARACTER LAKKHANGYAO | [0], [100], [101] | [fv3] + U+0E45 | fv2, Thai | |
| U+0E25 | ล | Thai | THAI CHARACTER LO LING | [0], [100], [101] | cons | Thai | |
| U+0E26 | ฦ | Thai | THAI CHARACTER LU | [0], [100], [101] | fv3 | Thai | |
| U+0E26 U+0E45 | ฦๅ | {Thai} | THAI CHARACTER LU + THAI CHARACTER LAKKHANGYAO | [0], [100], [101] | [fv3] + U+0E45 | fv2, Thai | |
| U+0E27 | ว | Thai | THAI CHARACTER WO WAEN | [0], [100], [101] | cons | Thai | |
| U+0E28 | ศ | Thai | THAI CHARACTER SO SALA | [0], [100], [101] | cons | Thai | |
| U+0E29 | ษ | Thai | THAI CHARACTER SO RUSI | [0], [100], [101] | cons | Thai | |
| U+0E2A | ส | Thai | THAI CHARACTER SO SUA | [0], [100], [101] | cons | Thai | |
| U+0E2B | ห | Thai | THAI CHARACTER HO HIP | [0], [100], [101] | cons | Thai | |
| U+0E2C | ฬ | Thai | THAI CHARACTER LO CHULA | [0], [100], [101] | cons | Thai | |
| U+0E2D | อ | Thai | THAI CHARACTER O ANG | [0], [100], [101] | cons | Thai | |
| U+0E2E | ฮ | Thai | THAI CHARACTER HO NOKHUK | [0], [100], [101] | cons | Thai | |
| U+0E30 | ะ | Thai | THAI CHARACTER SARA A | [0], [100], [101] | fv1 | follow-consonant-tone-sara-aa | Thai |
| U+0E31 | ั | Thai | THAI CHARACTER MAI HAN-AKAT | [0], [100], [101] | av | between-consonant-and-ct | Thai |
| U+0E32 | า | Thai | THAI CHARACTER SARA AA | [0], [100], [101] | fv1, sara-aa | follows-consonant-tone | Thai |
| U+0E34 | ิ | Thai | THAI CHARACTER SARA I | [0], [100], [101] | av | follows-consonant | Thai |
| U+0E35 | ี | Thai | THAI CHARACTER SARA II | [0], [100], [101] | av | follows-consonant | Thai |
| U+0E36 | ึ | Thai | THAI CHARACTER SARA UE | [0], [100], [101] | av | follows-consonant | Thai |
| U+0E37 | ื | Thai | THAI CHARACTER SARA UEE | [0], [100], [101] | av | follows-consonant | Thai |
| U+0E38 | ุ | Thai | THAI CHARACTER SARA U | [0], [100], [101] | bv | follows-consonant | Thai |
| U+0E39 | ู | Thai | THAI CHARACTER SARA UU | [0], [100], [101] | bv | follows-consonant | Thai |
| U+0E3A | ฺ | Thai | THAI CHARACTER PHINTHU | [0], [100], [101] | bd | follows-consonant | = phinthu; Thai |
| U+0E40 | เ | Thai | THAI CHARACTER SARA E | [0], [100], [101] | lv | precedes-consonant | Thai |
| U+0E41 | แ | Thai | THAI CHARACTER SARA AE | [0], [100], [101] | lv | precedes-consonant | Thai |
| U+0E42 | โ | Thai | THAI CHARACTER SARA O | [0], [100], [101] | lv | precedes-consonant | Thai |
| U+0E43 | ใ | Thai | THAI CHARACTER SARA AI MAIMUAN | [0], [100], [101] | lv | precedes-consonant | Thai |
| U+0E44 | ไ | Thai | THAI CHARACTER SARA AI MAIMALAI | [0], [100], [101] | lv | precedes-consonant | Thai |
| U+0E47 | ็ | Thai | THAI CHARACTER MAITAIKHU | [0], [100], [101] | ad | follows-consonant | = maitaikhu; Thai |
| U+0E48 | ่ | Thai | THAI CHARACTER MAI EK | [0], [100], [101] | tone | follows-consonant-av-bv | Thai |
| U+0E49 | ้ | Thai | THAI CHARACTER MAI THO | [0], [100], [101] | tone | follows-consonant-av-bv | Thai |
| U+0E4A | ๊ | Thai | THAI CHARACTER MAI TRI | [0], [100], [101] | tone | follows-consonant-av-bv | Thai |
| U+0E4B | ๋ | Thai | THAI CHARACTER MAI CHATTAWA | [0], [100], [101] | tone | follows-consonant-av-bv | Thai |
| U+0E4C | ์ | Thai | THAI CHARACTER THANTHAKHAT | [0], [100], [101] | ad | follows-consonant-av-bv | = thanthakhat; Thai |
| U+0E4D | ํ | Thai | THAI CHARACTER NIKHAHIT | [0], [100], [101] | ad | follows-consonant-av-bv | = nikhahit; Thai |
| U+0E4D U+0E32 | ํา | {Thai} | THAI CHARACTER NIKHAHIT + THAI CHARACTER SARA AA | [0], [100], [101] | [ad] + [fv1, sara-aa] | follows-consonant-tone | = sara am sequence; Thai |
Legend
Throughout this document, a code point sequence may be annotated with a string in ALL CAPS that is constructed on the same principle as a name for a Unicode Named Sequence. No claim is made that a sequence thus annotated is in fact a named sequence, nor that the annotation in such case actually corresponds to the formal name of a named sequence.
- 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. Sequences are annotated with a set of all distinct script values.
- Name
- Shows the character or sequence name from the Unicode Character Database. Named sequences are listed with their normative names, for ad-hoc sequences the individual names are shown separated by “+”.
- Ref
- Links to the references associated with the code point or sequence, if any.
- Tags
- LGR-defined tag values. Any tags matching the Unicode script property are suppressed in this view. For sequences, the tags for all member code points are shown in [] for information; sequences as such do not have tags.
- 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.
Variants
This LGR does not specify any variants.
Classes, Rules and Actions
Character Classes
| Number of named classes | 8 |
|---|---|
| Implicit (except script) | 5 |
| Implicit defined by script tag | 1 |
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 |
|---|---|---|---|---|---|
| above-vowel | Tag=av | 5 | {0E31 0E34-0E37} | Any Thai above vowel | |
| below-vowel | Tag=bv | 2 | {0E38-0E39} | Any Thai below vowel | |
| consonant | Tag=cons | 44 | {0E01-0E23 0E25 0E27-0E2E} | Any Thai consonant | |
| sara-aa | Tag=sara-aa | 1 | {0E32} | Thai SARA AA | |
| tone | Tag=tone | 4 | {0E48-0E4B} | Any Thai tone mark | |
| c-av-bv | combined = [[:consonant:] ∪ [:above-vowel:] ∪ [:below-vowel:]] |
51 | {0E01-0E23 0E25 0E27-0E2E 0E31 0E34-0E39} | Any Thai consonant, vowel-above or vowel-below | |
| ct | combined = [[:consonant:] ∪ [:tone:]] |
48 | {0E01-0E23 0E25 0E27-0E2E 0E48-0E4B} | Any Thai consonant or tone mark | |
| ctaa | combined = [[:consonant:] ∪ [:tone:] ∪ [:sara-aa:]] |
49 | {0E01-0E23 0E25 0E27-0E2E 0E32 0E48-0E4B} | Any Thai consonant, tone or sara-aa | |
| implicit | Tag=ad | 3 | {0E47 0E4C-0E4D} | Any character tagged as ad | |
| implicit | Tag=bd | 1 | {0E3A} | The character tagged as bd | |
| implicit | Tag=fv1 | 2 | {0E30 0E32} | Any character tagged as fv1 | |
| implicit | Tag=fv3 | 2 | {0E24 0E26} | Any character tagged as fv3 | |
| implicit | Tag=lv | 5 | {0E40-0E44} | Any character tagged as lv | |
| implicit | Tag=sc:Thai | 68 | {0E01-0E2E 0E30-0E32 0E34-0E3A 0E40-0E44 0E47-0E4D} | Any character tagged as Thai |
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.
- Combined
- A named class defined by set operations on other classes using the following syntax:
- [: :] - named or implicit character set
- Reference to a named character set [:name:] or an implicit character set [:tag:]. A leading “^” before name or tag indicates the set complement.
- ∪, ∩, ∖, ∆ - set operators
- Sets may be combined by set operators (∪ = union, ∩ = intersection, ∖ = difference, ∆ = symmetric difference).
Whole Label Evaluation and Context Rules
| Number of rules | 7 |
|---|---|
| Used to trigger actions | 1 |
| Used as context rule (C) | 6 |
| Anchored context rules | 6 |
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}]] |
✔ | Default WLE rule matching labels with leading combining marks ⍟ | |||
| precedes-consonant | ⚓︎ →([:consonant:]) |
✔ | C | WLE 7.2: check if current cp is preceding a consonant | ||
| follows-consonant | ([:consonant:])← ⚓︎ |
✔ | C | WLE 7.3: check if current cp is following a consonant | ||
| between-consonant-and-ct | ([:consonant:])← ⚓︎ →([:ct:]) |
✔ | C | WLE 7.4: check if current cp is in between a consonant and either tone or consonant | ||
| follow-consonant-tone-sara-aa | ([:ctaa:])← ⚓︎ |
✔ | C | WLE 7.5: U+0E30 (THAI CHARACTER SARA A, ะ) can follow a consonant, a tone or U+0E32 (THAI CHARACTER SARA AA, า) | ||
| follows-consonant-tone | ([:ct:])← ⚓︎ |
✔ | C | WLE 7.6, 7.9: check if current cp is following a consonant or a tone | ||
| follows-consonant-av-bv | ([:c-av-bv:])← ⚓︎ |
✔ | C | WLE 7.7, 7.8: A tone-mark, THANTHAKHAT, NIKHAHIT can only follow a consonant, above-vowel or below-vowel |
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.
- start or end
- (start) matches the start of the label; (end) matches the end of the label.
- [: :] - named or implicit character set
- Reference to a named character set [:name:] or an implicit character set [:tag:]. A leading “^” before name or tag indicates the set complement.
- [\p{ }] - property
- 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.
- ⍟ - default rule
- Rules marked with ⍟ are included by default and may or may not be triggered by any possible label under this LGR.
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 | labels with leading combining marks are invalid ⍟ | |
| 2 | if at least one variant is in | {out-of-repertoire-var} | → | invalid | any variant label with a code point out of repertoire is invalid ⍟ | |
| 3 | if at least one variant is in | {blocked} | → | blocked | any variant label containing blocked variants is blocked ⍟ | |
| 4 | if each variant is in | {allocatable} | → | allocatable | variant labels with all variants allocatable are allocatable ⍟ | |
| 5 | 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.
- ⍟ - default action
- Actions marked with ⍟ are included by default and may or may not be triggered by any possible label under this LGR.
Note: The following variant types are used in one or more actions, but are not defined in this LGR: allocatable, blocked, out-of-repertoire-var. This is not necessarily an error.
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 Standard, Version 1.1 Any code point originally encoded in Unicode Version 1.1 |
| [100] | Thai Industrial Standard (TIS) 1566-2541(1988) https://www.ratchakitcha.soc.go.th/DATA/PDF/2542/E/088/9.PDF |
| [101] | Computers and the Thai Language https://lexitron.nectec.or.th/KM_HL5001/file_HL5001/Paper/Inter%20Journal/krrn_52085.pdf |