Root Zone LGR for script: Thai (Thai) | rz-lgr-5-thai-script-26may22-en |
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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 | 2022-05-26 |
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LGR Version | 5 (Root Zone LGR for the Thai Script) |
Language | und-Thai (Thai Script) |
Scope | domain: "." (Root) |
Unicode Version | 11.0.0 |
This file contains 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-5]. The format of this file follows [RFC 7940].
In addition to the 68 single code points according to Section 5 “Repertoire” in [Proposal-Thai], three sequences have been defined. 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 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 based on [MSR-5], which is a subset of [Unicode 11.0].
As part of the Root Zone, this LGR includes neither decimal digits nor the HYPHEN-MINUS.
Each code point is tagged with the script or scripts with which the code point is used, one or more other character categories, and one or more references documenting sufficient justification for inclusion in the repertoire; see “References” below. Comments identify the language using the code point.
According to Section 6, “Variants” in [Proposal-Thai], this LGR defines no variants.
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].
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.
The LGR includes the set of required default WLE rules and actions applicable to the Root Zone and defined in [MSR-5]. They are marked with ⍟.
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:
The Root Zone LGR for the Thai script was developed by the Thai Generation Panel. For methodology and contributors, see Sections 4 and 8 in [Proposal-Thai], as well as [RZ-LGR-5-Overview].
The following general references are cited in this document:
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.
Number of elements in repertoire | 71 |
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Number of code points | 68 |
Number of sequences | 3 |
Longest code point sequence | 2 |
Code points defined via sequence | 1 |
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 |
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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 |
Throughout this LGR, 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.
This LGR does not specify any variants.
Number of named classes | 8 |
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Implicit (except script) | 5 |
Implict 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 |
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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 |
Number of rules | 7 |
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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 |
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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, NIKAHIT can only follow a consonant, above-vowel or below-vowel |
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 | |
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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) ⍟ |
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 1.1 Any code point originally encoded in Unicode 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 |