Reference LGR for script: Lao (Laoo) lgr-second-level-lao-script-22apr21-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 2021-04-22
LGR Version 2 (Second Level Reference LGR)
Language und-Laoo (Lao Script)
Unicode Version 6.3.0

Table of Contents

1 Description

Reference Label Generation Rules for the Lao Script


This document specifies a reference set of Label Generation Rules (LGR) for the Lao script for the second level. The starting point for the development of this LGR can be found in the related Root Zone LGR [RZ-LGR-4-Laoo]. For details and additional background on the script, see "Proposal for a Lao Script Root Zone LGR [Proposal-Lao]". The format of this file follows [RFC 7940].


The repertoire contains 51 code points for letters; in addition, 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 Lao script. The repertoire is a subset of [Unicode 6.3]. For details, see Section 5 “Repertoire” in [Proposal-Lao]. (The proposal cited has been adopted for the Lao script portion of the Root Zone LGR.)

For the second level, the repertoire has been augmented with the ASCII digits, U+0030 (0) to U+0039 (9), Lao digits, U+0ED0 (໐) to U+0ED9 (໙), and U+002D (-) HYPHEN-MINUS for a total of 73 repertoire elements.

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.


This LGR defines no variants for letters. See Section 6, "Variants" in [Proposal-Lao].

Digit Variants: All Lao digits are treated as semantic variants of the corresponding common (ASCII) digits. By transitivity, they are also semantic variants of any native digits in scripts that also include the common digits. Such transitive relations are deemed to exist implicitly but are not listed explicitly in each reference LGR. (Omitting the listing of these other cross script digit variants does not affect index variant calculation, as the ASCII digit variant being smallest would always be the index variant.) There is a strong resemblance between Thai and Khmer digits, and certain Lao digits. In addition, Lao digit ZERO is a cross-script homoglyph or near homoglyph of digit ZERO in many other scripts; all of these are already implicit semantic variants by transitivity and therefore not listed here. To keep digit variant sets manageable in zones where multiple scripts are present, no attempt has been made at identifying cross-script variants among digits of different numeric value or between a digit in one script and a letter in another, such as between digit zero and Latin letter 'o'. Other mechanisms may be required to prevent homograph labels.

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]).

Lao Digits: U+0E50 (๐) to U+0E59 (๙) are a set of Lao-specific digits. They are used in alternation with the European (common) digits.

Common Digits: U+0030 (0) to U+0039 (9) are the set of digits from the ASCII range.

Whole Label Evaluation (WLE) and Context Rules

Common Rules

Default Actions

Actions include the default actions for LGRs as well as that needed to invalidate labels with misplaced combining marks. They are marked with ⍟. For a description see [RFC 7940].

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:

No context rules apply to “consonant” code points. For discussion, see Section 5.1, “Consonants” in [Proposal-Lao].

Methodology and Contributors

This reference LGR for Lao for the 2nd Level has been developed by Michel Suignard and Asmus Freytag, based on the Root Zone LGR for Lao and information contained or referenced therein, see [RZ-LGR-4-Laoo]. Suitable extensions for the second level have been applied according to the [Guidelines]. The original proposal for a Root Zone LGR for the Lao script, that this reference LGR is based on, was developed by the Lao Generation Panel. For more information on methodology and contributors to the underlying Root Zone LGR, see Sections 4 and 8 in [Proposal-Lao], as well as [RZ-LGR-Overview].

Changes from Version 1

Comments for Lao digits have been corrected.


The following general references are cited in this document:

ICANN, "Guidelines for Developing Reference LGRs for the Second Level, (Los Angeles, California: ICANN, 27 May 2020),
Lao Generation Panel, "Proposal for Lao Script Root Zone LGR",
[RFC 7940]
Davies, K. and A. Freytag, "Representing Label Generation Rulesets Using XML", RFC 7940, August 2016,
Integration Panel, "Root Zone Label Generation Rules - LGR-4: Overview and Summary", 5 November 2020 (PDF),
ICANN, Root Zone Label Generation Rules for the Lao Script (und-Laoo) , 5 November 2020 (XML)
[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)

For references consulted particularly in designing the repertoire for the Lao script for the second level. please see details in the Table of References below. Reference [0] refers to Unicode Standard version in which corresponding code points were initially encoded. References [201], [202], [203], [204], 205], [206], & [207] correspond to sources justifying the inclusion of or classification for the corresponding code points. Entries in the table may have multiple source reference values. Reference [150] indicates the source for common rules.

2 Repertoire

Repertoire Summary

Number of elements in repertoire 73
Number of code points
for each script
Lao 61
Common 11
Number of code points 72
Number of sequences 1
Longest code point sequence 2

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.

For any code point or sequence for which a variant is defined, additional information is provided in the Variants column. See also the legend provided below the table.

Glyph Script Name Ref Tags Required Context Variants Comment
U+002D - Common HYPHEN-MINUS [0] Hyphen not: hyphen-minus-disallowed  
U+0030 0 Common DIGIT ZERO [0] Common-digit   set 1
U+0031 1 Common DIGIT ONE [0] Common-digit   set 2
U+0032 2 Common DIGIT TWO [0] Common-digit   set 3
U+0033 3 Common DIGIT THREE [0] Common-digit   set 4
U+0034 4 Common DIGIT FOUR [0] Common-digit   set 5
U+0035 5 Common DIGIT FIVE [0] Common-digit   set 6
U+0036 6 Common DIGIT SIX [0] Common-digit   set 7
U+0037 7 Common DIGIT SEVEN [0] Common-digit   set 8
U+0038 8 Common DIGIT EIGHT [0] Common-digit   set 9
U+0039 9 Common DIGIT NINE [0] Common-digit   set 10
U+0E81 Lao LAO LETTER KO [0], [201], [204] Cf, consonant     Lao
U+0E82 Lao LAO LETTER KHO SUNG [0], [201], [204] consonant     Lao
U+0E84 Lao LAO LETTER KHO TAM [0], [201], [204] consonant     Lao
U+0E87 Lao LAO LETTER NGO [0], [201], [204] Cf, consonant     Lao
U+0E88 Lao LAO LETTER CO [0], [201], [204] consonant     Lao
U+0E8A Lao LAO LETTER SO TAM [0], [201], [204] Cf, consonant     Lao
U+0E8D Lao LAO LETTER NYO [0], [201], [204] Cf, consonant     Lao
U+0E94 Lao LAO LETTER DO [0], [201], [204] Cf, consonant     Lao
U+0E95 Lao LAO LETTER TO [0], [201], [204] consonant     Lao
U+0E96 Lao LAO LETTER THO SUNG [0], [201], [204] consonant     Lao
U+0E97 Lao LAO LETTER THO TAM [0], [201], [204] Cf, consonant     Lao
U+0E99 Lao LAO LETTER NO [0], [201], [204] Cf, consonant     Lao
U+0E9A Lao LAO LETTER BO [0], [201], [204] Cf, consonant     Lao
U+0E9B Lao LAO LETTER PO [0], [201], [204] consonant     Lao
U+0E9C Lao LAO LETTER PHO SUNG [0], [201], [204] consonant     Lao
U+0E9D Lao LAO LETTER FO FON [0], [201], [204] consonant     = lao letter fo sung; Lao
U+0E9E Lao LAO LETTER PHO TAM [0], [201], [204] consonant     Lao
U+0E9F Lao LAO LETTER FO FAY [0], [201], [204] Cf, consonant     = lao letter fo tam; Lao
U+0EA1 Lao LAO LETTER MO [0], [201], [204] Cf, consonant     Lao
U+0EA2 Lao LAO LETTER YO [0], [201], [204] consonant     Lao
U+0EA3 Lao LAO LETTER RO [0], [204] Cf, consonant     = lao letter lo rada; Lao
U+0EA5 Lao LAO LETTER LO [0], [201], [204] Cf, consonant     = lao letter lo ling; Lao
U+0EA7 Lao LAO LETTER WO [0], [201], [204], [205] Cf, consonant     Lao
U+0EAA Lao LAO LETTER SO SUNG [0], [201], [204] Cf, consonant     Lao
U+0EAB Lao LAO LETTER HO SUNG [0], [201], [204] consonant     Lao
U+0EAD Lao LAO LETTER O [0], [201], [204], [205] consonant     Lao
U+0EAE Lao LAO LETTER HO TAM [0], [201], [204] consonant     Lao
U+0EB0 Lao LAO VOWEL SIGN A [0], [201], [205], [206] vowel-after follows-C-tonemark-vabove   Lao
U+0EB1 Lao LAO VOWEL SIGN MAI KAN [0], [201], [205], [206] vowel-above follows-main-consonant   Lao
U+0EB2 Lao LAO VOWEL SIGN AA [0], [201], [205], [206] vowel-after follows-C-tonemark-vabove   Lao
U+0EB2 U+0EB0 າະ {Lao} LAO VOWEL SIGN AA + LAO VOWEL SIGN A [205] [vowel-after] + [vowel-after] follows-vbefore-consonant-cluster   Lao
U+0EB4 Lao LAO VOWEL SIGN I [0], [201], [205], [206] vowel-above follows-main-consonant   Lao
U+0EB5 Lao LAO VOWEL SIGN II [0], [201], [205], [206] vowel-above follows-main-consonant   Lao
U+0EB6 Lao LAO VOWEL SIGN Y [0], [201], [205], [206] vowel-above follows-main-consonant   Lao
U+0EB7 Lao LAO VOWEL SIGN YY [0], [201], [205], [206] vowel-above follows-main-consonant   Lao
U+0EB8 Lao LAO VOWEL SIGN U [0], [201], [205], [206] vowel-below follows-main-consonant   Lao
U+0EB9 Lao LAO VOWEL SIGN UU [0], [201], [205], [206] vowel-below follows-main-consonant   Lao
U+0EBB Lao LAO VOWEL SIGN MAI KON [0], [205] vowel-above follows-main-consonant   Lao
U+0EBC Lao LAO SEMIVOWEL SIGN LO [0], [201], [205], [206] semi-consonant follows-consonant   = lao semiconsonant lo; Lao
U+0EBD Lao LAO SEMIVOWEL SIGN NYO [0], [201], [205] vowel-after follows-C-tonemark-vabove   = lao semivowel ia; Lao
U+0EC0 Lao LAO VOWEL SIGN E [0], [201], [205], [206] vowel-before precedes-consonant   Lao
U+0EC1 Lao LAO VOWEL SIGN EI [0], [201], [205], [206] vowel-before precedes-consonant   Lao
U+0EC2 Lao LAO VOWEL SIGN O [0], [201], [205], [206] vowel-before precedes-consonant   Lao
U+0EC3 Lao LAO VOWEL SIGN AY [0], [201], [205], [206] vowel-before precedes-consonant   Lao
U+0EC4 Lao LAO VOWEL SIGN AI [0], [201], [205], [206] vowel-before precedes-consonant   Lao
U+0EC6 Lao LAO KO LA [0], [203] sign repetition-mark-limit   = lao may sam; Lao
U+0EC8 Lao LAO TONE MAI EK [0], [202] tone-mark follows-C-vabove-vbelow   Lao
U+0EC9 Lao LAO TONE MAI THO [0], [202] tone-mark follows-C-vabove-vbelow   Lao
U+0ECA Lao LAO TONE MAI TI [0], [202] tone-mark follows-C-vabove-vbelow   Lao
U+0ECB Lao LAO TONE MAI CATAWA [0], [202] tone-mark follows-C-vabove-vbelow   = lao tone mai jattawa; Lao
U+0ECC Lao LAO CANCELLATION MARK [0], [207] sign follows-Cf   = lao mark mai ka lan; Lao
U+0ECD Lao LAO NIGGAHITA [0], [201], [205], [206] vowel-above follows-main-consonant   = lao vowel sign or; Lao
U+0ED0 Lao LAO DIGIT ZERO [0] Lao-digit   set 1  
U+0ED1 Lao LAO DIGIT ONE [0] Lao-digit   set 2  
U+0ED2 Lao LAO DIGIT TWO [0] Lao-digit   set 3  
U+0ED3 Lao LAO DIGIT THREE [0] Lao-digit   set 4  
U+0ED4 Lao LAO DIGIT FOUR [0] Lao-digit   set 5  
U+0ED5 Lao LAO DIGIT FIVE [0] Lao-digit   set 6  
U+0ED6 Lao LAO DIGIT SIX [0] Lao-digit   set 7  
U+0ED7 Lao LAO DIGIT SEVEN [0] Lao-digit   set 8  
U+0ED8 Lao LAO DIGIT EIGHT [0] Lao-digit   set 9  
U+0ED9 Lao LAO DIGIT NINE [0] Lao-digit   set 10  


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.

Code Point
A code point or code point sequence.
The shape displayed depends on the fonts available to your browser.
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.
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 “+”.
Links to the references associated with the code point or sequence, if any.
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.
Link to the variant set the code point or sequence is a member of, except where a coded point or sequence maps only to itself, in which case the type of that mapping is listed.
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.

3 Variant Sets

Variant Set Summary

Number of variant sets 10
Largest variant set 2
Variants by Type
blocked 20

The following tables list all variant sets defined in this LGR, except for singleton sets. Each table lists all variant mapping pairs of the set; one per row. Mappings are assumed to be symmetric: each row documents both forward (→) and reverse (←) mapping directions. In each table, the mappings are sorted by Source value in ascending code point order; shading is used to group mappings from the same source code point or sequence.

Where the type of both forward and reverse mappings are the same, a single value is given in the Type column; otherwise the types for forward and reverse mappings, as well as comments and references, are listed above one another. For summary counts, both forward and reverse mappings are always counted separately.

In any LGR with variant specifications that are well behaved, all members within each variant set are defined as variants of each other; the mappings in each set are symmetric and transitive; and all variant sets are disjoint.

Common Legend

By convention, the smaller of the two code points in a variant mapping pair.
By convention, the larger of the two code points in a variant mapping pair.
The shape displayed for source or target depends on the fonts available to your browser.
- forward
Indicates that Type, Ref and Comment apply to the mapping from source to target.
- reverse
Indicates that Type, Ref and Comment apply to the reverse mapping from target to source.
- both
Indicates that Type, Ref and Comment apply to both forward and reverse mapping.
The type of the variant mapping. There are some predefined variant types such as “allocatable” and “blocked”, while others are defined specifically for each LGR.
One or more reference IDs (optional). A “/” separates references for reverse / forward mappings, if different.
A descriptive comment (optional). A “/” separates comments for reverse / forward mappings, if different.

Variant Set 1 — 2 Members

Source Glyph Target Glyph   Type Ref Comment
0030 0 0ED0 blocked   ASCII digit variant / Lao digit variant

Variant Set 2 — 2 Members

Source Glyph Target Glyph   Type Ref Comment
0031 1 0ED1 blocked   ASCII digit variant / Lao digit variant

Variant Set 3 — 2 Members

Source Glyph Target Glyph   Type Ref Comment
0032 2 0ED2 blocked   ASCII digit variant / Lao digit variant

Variant Set 4 — 2 Members

Source Glyph Target Glyph   Type Ref Comment
0033 3 0ED3 blocked   ASCII digit variant / Lao digit variant

Variant Set 5 — 2 Members

Source Glyph Target Glyph   Type Ref Comment
0034 4 0ED4 blocked   ASCII digit variant / Lao digit variant

Variant Set 6 — 2 Members

Source Glyph Target Glyph   Type Ref Comment
0035 5 0ED5 blocked   ASCII digit variant / Lao digit variant

Variant Set 7 — 2 Members

Source Glyph Target Glyph   Type Ref Comment
0036 6 0ED6 blocked   ASCII digit variant / Lao digit variant

Variant Set 8 — 2 Members

Source Glyph Target Glyph   Type Ref Comment
0037 7 0ED7 blocked   ASCII digit variant / Lao digit variant

Variant Set 9 — 2 Members

Source Glyph Target Glyph   Type Ref Comment
0038 8 0ED8 blocked   ASCII digit variant / Lao digit variant

Variant Set 10 — 2 Members

Source Glyph Target Glyph   Type Ref Comment
0039 9 0ED9 blocked   ASCII digit variant / Lao digit variant

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
Cf Tag=Cf 14 {0E81 0E87 0E8A 0E8D 0E94 0E97 0E99-0E9A 0E9F 0EA1 0EA3 0EA5 0EA7 0EAA}   Any Lao final consonant
consonant Tag=consonant 27 {0E81-0E82 0E84 0E87-0E88 0E8A 0E8D 0E94-0E97 0E99-0E9F 0EA1-0EA3 0EA5 0EA7 0EAA-0EAB 0EAD-0EAE}   Any Lao consonant
semi-consonant Tag=semi-consonant 1 {0EBC}   Lao semi-consonant LO
tone-mark Tag=tone-mark 4 {0EC8-0ECB}   Any Lao one mark
vowel-above Tag=vowel-above 7 {0EB1 0EB4-0EB7 0EBB 0ECD}   Any Lao vowel above
vowel-below Tag=vowel-below 2 {0EB8-0EB9}   Any Lao vowel below
common-digits Tag=Common-digit 10 {0030-0039}   Digits from the ASCII range; ⍟
lao-digits Tag=Lao-digit 10 {0ED0-0ED9}   Lao digits
hyphen Tag=Hyphen 1 {002D}   The Hyphen-minus character ⍟
implicit Tag=sign 2 {0EC6 0ECC}   Any character tagged as sign
implicit Tag=vowel-after 3 {0EB0 0EB2 0EBD}   Any character tagged as vowel-after
implicit Tag=vowel-before 5 {0EC0-0EC4}   Any character tagged as vowel-before
implicit Tag=sc:Laoo 61 {0E81-0E82 0E84 0E87-0E88 0E8A 0E8D 0E94-0E97 0E99-0E9F 0EA1-0EA3 0EA5 0EA7 0EAA-0EAB 0EAD-0EAE 0EB0-0EB2 0EB4-0EB9 0EBB-0EBD 0EC0-0EC4 0EC6 0EC8-0ECD 0ED0-...}   Any character tagged as Lao
implicit Tag=sc:Zyyy 11 {002D 0030-0039}   Any character tagged as Common


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 "...".
A named or implicit class defined by all code points that share the given tag value (ttt).
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
Anchor Used as
Ref Comment
leading-combining-mark (start)[[\p{gc=Mn}] ∪ [∅=\p{gc=Mc}]]     [150] RFC 5891 restrictions on placement of combining marks ⍟
hyphen-minus-disallowed (((start))← ⚓)|(⚓ →((end)))|(((start)..[:hyphen:])← ⚓)   C [150] RFC 5891 restrictions on placement of U+002D (-) ⍟
follows-consonant ([:consonant:])← ⚓   C   WLE Rule 1: A semi-consonant must follow a consonant
precedes-consonant ⚓ →([:consonant:])   C   WLE Rule 2: A vowel-before precedes a main consonant cluster
follows-main-consonant ([:consonant:]|[:semi-consonant:])← ⚓   C   WLE Rule 3: A vowel-above, and vowel-below follow a main consonant C
follows-C-tonemark-vabove ([:consonant:]|[:semi-consonant:]|[:tone-mark:]|[:vowel-above:])← ⚓   C   WLE Rule 4: A vowel-after follows a main consonant, tone-mark or vowel-above
consonant-cluster [:consonant:]{1,2}[:semi-consonant:]?         Defining consonant cluster for WLE Rule 5
follows-vbefore-consonant-cluster (\u0EC0(:consonant-cluster:))← ⚓   C   WLE Rule 5: The sequence U+0EB2 U+0EB0 (າະ) follows a vowel before, and a consonant cluster
follows-C-vabove-vbelow ([:consonant:]|[:semi-consonant:]|[:vowel-above:]|[:vowel-below:])← ⚓   C   WLE Rule 6: A tone-mark follows a main consonant, vowel-above or vowel-below
follows-Cf ([:Cf:])← ⚓   C   WLE Rule 7: The sign U+0ECC (໌) can only occur after final consonants
repetition-mark-limit ⚓ →(\u0EC6{0,2}(end))   C   WLE Rule 8: The sign U+0EC6 (ໆ) can only occur 0 to 3 times at the end of the label
digit-mixing ([:common-digits:].*[:lao-digits:])|([:lao-digits:].*[:common-digits:])       restrictions on mixing digits


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.
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.
(: :) - rule reference
Non-recursive reference to a named rule.
(... | ...) - 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.
*, +, ?, {n,m} - count operators
* indicates 0 or more, + indicates one or more, and ? indicates up to one instance. {n,m} indicates at least n and at most m instances.
[: :] - 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 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.
⍟ - default rule
Rules marked with ⍟ are included by default and may or may not be triggered by any possible label under this LGR.

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 [150] 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 label matches digit-mixing invalid   a label violating the restriction on digit mixing is invalid
4 if at least one variant is in {blocked} blocked   any variant label containing blocked variants is blocked ⍟
5 if each variant is in {allocatable} allocatable   variant labels with all variants allocatable are allocatable ⍟
6 if any label (catch-all)   valid   catch all (default action) ⍟


{...} - 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.

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 Standard 1.1
Any code point originally encoded in Unicode 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]
[150] RFC 5891, Internationalized Domain Names in Applications (IDNA): Protocol