Root Zone Label Generation Rules for the Malayalam script

Overview

This file contains Label Generation Rules (LGR) for the Malayalam script for the Root Zone. For details on the development of this LGR and additional background on the script, see “Proposal for a Malayalam Script Root Zone Label Generation Ruleset (LGR)” [Proposal-Malayalam]. 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].

Repertoire

The repertoire contains 70 code points for letters used in the Malayalam language in addition to 11 sequences used in defining variants, bringing the total repertoire entries to 81.

For more detail, see Section 5, “Repertoire” in [Proposal-Malayalam].

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.

Code points outside the Malayalam script that are listed in this file are targets for out-of-script variants and are identified by a reflexive (identity) variant of type “out-of-repertoire-var”. They do not form part of the repertoire.

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.

Variants

This LGR defines in-script variants and cross-script variants as described in Section 6, “Variants”, in [Proposal-Malayalam]. One in-script variant is due to the multiple ways to write the conjunct “nta” in Malayalam. Cross-script variants for related scripts are mainly defined for Tamil code points, as well as for Oriya and Myanmar.

For consistency with other RZ-LGRs, cross-script variants to ASCII code points are listed explicitly as well. For the Malayalam LGR this requires the addition of one redundant sequence U+0D1F U+0D1F (ടട). This sequence has no effect on available labels.

Variant Disposition: All variants are of type “blocked”, making labels that differ only by these variants mutually exclusive: whichever label containing either of these variants is chosen earlier, the other one equivalent variant label should be blocked. There is no preference among these variants.

This LGR does not define allocatable variants.

Additional Variants: This LGR inherits additional blocked cross-script variants by integration; they may not be listed here unless they result in in-script variants. See the merged, Common LGR [RZ-LGR-5] for details of all applicable cross-script variants, including any not listed here; always use the Common LGR for determining cross-script collisions of labels.

The specification of variants in the Root Zone LGR follows the guidelines in [RFC 8228].

Context Rules for Variants: some of the variants defined in this LGR are “effective null variants”, that is, some code points in the source map to “nothing” in the target with all other code points unchanged. (Because mappings are symmetric, it does not matter whether it is the forward or reverse mapping that maps to “null” ). Such variants require a context rule to keep the variant set well-behaved. Symmetry requires the same context rule for both forward and reverse mappings.

In other cases, the sequences or code points making up source and target are constrained by context rules on the code points. In such a case, any variants require context rules that match the intersection between the contexts for both source and target; otherwise a sequence might be considered valid in some variant label when it would not be valid in an equivalent context in an original label.

Character Classes

The basic characters in Malayalam are classified here into the following categories: Consonants, Vowels, Matra and Reordrant Vowel Diacritics, Halant, Visarga, Anusvara and Chillu letters.

Consonant: Malayalam is written in an abugida script derived ultimately from Brahmi in which every consonant carries an inherent /a/. More details in Section 3.8, “The Structure of Malayalam Script” of [Proposal-Malayalam].

Vowels: Like consonants, the independent vowels can follow any other class of code points in a label.

Matra: Vowels other than the inherent vowel are written as vowel diacritics. They are referred to as Matras, when they follow consonants. More details in Section 3.8, “The Structure of Malayalam Script” of [Proposal-Malayalam].

Halant: A consonant can be combined with another consonant or conjunct using the halant encoded as U+0D4D ( ്) MALAYALAM SIGN VIRAMA. This strips off the implicit vowel. More details in Section 3.8, “The Structure of Malayalam Script” of [Proposal-Malayalam].

Anusvara: In Malayalam, anusvara represented as U+0D02 ( ം), simply represents a consonant /m/ after a vowel, though this /m/ may be assimilated to another nasal consonant. More details in Section 3.8, “The Structure of Malayalam Script” of [Proposal-Malayalam].

Visarga: The visarga represents a consonant /h/ after a vowel, and is transliterated as ḥ. Like the anusvara, it is a special symbol, and is never followed by an inherent vowel or another vowel. More details in Section 3.8, “The Structure of Malayalam Script” of [Proposal-Malayalam].

Chillu: Chillu letters, aka “Chillaksharam”, represent pure consonants without any vowel sound. More details in Section 3.8, “The Structure of Malayalam Script” of [Proposal-Malayalam].

Reordrant: Vowel diacritics, part of which reorder around the preceding character or conjunct. More details in Sections 6.1 “In-script Variants” and 7.1.1 “Variables or definitions” of [Proposal-Malayalam].

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-5]. 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.

Malayalam-specific Rules

There are constraints on the context for many of the character classes in Malayalam. A corresponding set of context and whole label rules has been formulated for LGR specification, as described in Section 7, “Whole Label Evaluation (WLE) Rules” in [Proposal-Malayalam].

The following symbols are used in the WLE rules:
C → Consonant
M → Matra
V → Vowel
B → Anusvara
X → Visarga
D → Chandrabindu
H → Halant
L → Chillu
R → Reordrant Matra

Note: the Reordrant Matras include one sequence. That requires an auxiliary rule R in addition to class R.

The rules are:

• 1. H: must be preceded by C or U+0D41 ( ു)
• 2. M: must be preceded by C
• 3. B: must be preceded by C, V or M
• 4. X: must be preceded by C, V or M
• 5. L: cannot be preceded by B, X or H
• 6. A label does not begin with L

The following context rules apply to Consonants U+0D33 (ള) LLA and U+0D31 (റ) RRA as well as to sequences ending in these code points:

• 7. The character U+0D33 (ള) cannot immediately follow U+0D33 (ള), except as part of a defined sequence
• 8. The character U+0D31 (റ) cannot immediately follow U+0D31 (റ), except as part of a defined sequence

Note: the implementation of Rules 7 & 8 relies on the fact that a context rule is not evaluated between code points in the same sequence. For example, if a label contains two adjacent U+0D33 U+0D33 (ളള) surrounded by other code points , the two code points can only be interpreted as the sequence U+0D33 U+0D33 (ളള) because a singleton U+0D33 (ള) is not allowed to be followed by another U+0D33 (ള).

The following context rule applies to the sequence Chillu N + Halant (U+0D7B U+0D4D):

• 9. The sequence U+0D7B U+0D4D (ൻ്) must be preceded by C, L, M, V and must be followed by U+0D31 (റ)

Context rules for Variants

The following context rules apply to variants:

• V1: A variant is defined when followed by U+0D31 (റ)
• V2: A variant preceded by 0D33+Halant or followed by R or Halant+0D33 is not defined
• V3: A variant preceded by 0D31+Halant or followed by R or Halant+0D31 is not defined

These rules ensure that the variant label sets are well-behaved in cases where variant sequences overlap.

Note: any sequences ending with 0D31 would overlap with the various variant sequences beginning with 0D31, therefore this LGR drops the 0D31 from the end of these sequences, but adds context rule V1, when="followed-by-0D31" instead. Because all the variants also end in 0D31, this results in the same generated variants as if the sequences had been defined with trailing U+0D31 (റ), but now the variants are well-behaved in all contexts.

More details in Section 6.1, “In-script Variants” and Section 7, “Whole Label Evaluation Rules (WLE)” of [Proposal-Malayalam]

There are a number of cross-script homoglyphs to U+0D31 (റ) RRA, which would interact with the definition of in-script sequences and variants, leading to unacceptable complexity. These variants would affect only labels made solely of letters RRA, and no other labels. Rule 8 already restricts labels consisting solely of copies of the letter RRA to either “റ” or “ററ”, thus allowing only two such labels. The following rule disallows the remaining two possible labels, obviating any need to define these cross-script variants.

• 10. A label cannot consist solely of letters U+0D31 (റ) RRA

Malayalam-specific actions

WLE rules 6 and 10 trigger Malayalam-specific actions to invalidate any original and variant labels not satisfying the constraints. See Section 7, “Whole Label Evaluation (WLE) Rules” in [Proposal-Malayalam].

Methodology and Contributors

The Root Zone LGR for the Malayalam script was developed by the Neo-Brahmi Generation Panel (NBGP) the members of which have experience in linguistics and computational linguistics in a wide variety of languages written with Neo-Brahmi scripts. Under the Neo-Brahmi Generation Panel, there are nine scripts belonging to separate Unicode blocks. Each of these scripts has been assigned a separate LGR, with the Neo-Brahmi GP ensuring that the fundamental philosophy behind building each LGR is in sync with all other Brahmi-derived scripts. For further details on methodology and contributors, see Sections 4 and 8 in [Proposal-Malayalam], as well as [RZ-LGR-5-Overview].

Changes from LGR-3

This LGR has been updated for LGR-4 to address an inconsistency involving the conjunct “nta” and to eliminate some potentially complex interactions with cross-script variants. For the prior version see [RZ-LGR-3-Mlym].

1. Removed Chillu N from rule 1 and added a new context rule applied to the sequence Chillu N + Halant (U+0D7B U+0D4D):

   • 9. The sequence U+0D7B U+0D4D (ൻ്) must be preceded by C, L, M, V and must be followed by U+0D31 (റ)

   This change disallows some contexts that should not have been allowed for U+0D4D ( ്) when following U+0D7B (ൻ).

2. Added a new context rule applied to variants:

   • V1: A variant is defined when followed by U+0D31 (റ)

   The definition of the sequences to which this context rule applies has been changed by dropping the final U+0D31 (റ). This is an equivalent formulation. The change simplifies the formulation of other rules and variant definitions.

3. Added a new whole-label rule (and corresponding action):

   • 10. A label cannot consist solely of letters U+0D31 (റ) RRA

   This rule invalidates the two labels U+0D31 (റ) and U+0D31 U+0D31 (ററ), obviating the need to define certain cross-script variants for U+0D31 (റ)

Note: as result of the update, the LGR is slightly more restrictive.

Changes from LGR-4

As result of integration with additional scripts, this LGR has been updated. This update does not change the set of labels available under this LGR. For the prior version see [RZ-LGR-4-Mlym].

Integration with scripts newly added to LGR-5 adds cross-script variants to ASCII code points, such as between U+00^F and U+0D20 (ഠ), or between U+0073 (s) and U+0D1F (ട). For the latter, the Latin LGR [RZ-LGR-Latin] also declares an in-script variant between U+0073 U+0073 (ss) and U+00DF (ß), requiring the definition of a sequence U+0073 U+0073 (ss). Therefore the sequence U+0073 U+0073 (ss) automatically inherits a variant to any sequence U+0D1F U+0D1F (ടട) occurring in a Malayalam label. Transitivity of variants on the code point level requires explicit declaration of a sequence U+0D1F U+0D1F (ടട). Except for the purposes of allowing a variant, that sequence would not need to be defined in the Malayalam LGR because it is redundant: the LGR already supports the repetition of the singleton code point U+0D1F (ട) without restriction.

Even though cross-script variants with the Latin or other scripts with cross-script variants to U+0D1F (ട) are not otherwise listed in this LGR, the sequence U+0D1F U+0D1F (ടട) has been added here exceptionally, as have the variants between U+0073 (s) and U+0D1F (ട). Doing so ensures that the sequence forms part of the merged repertoire in Common LGR [RZ-LGR-5] and that any cross-script variants defined for it can be computed using that LGR. Being redundant other than in the definition of variants, adding the sequence does not change the labels available under this LGR.

Note that the listing of variants for U+0D1F (ട) and U+0D1F U+0D1F (ടട) in this LGR is that minimally required for integration. Additional cross-script variants for these repertoire elements exist and are defined in [RZ-LGR-5].For consistency across RZ-LGRs, imposed variants to ASCII code points and to the Myanmar script are now explicitly listed as well

.

References

The following general references are cited in this document:

[MSR-5]

Integration Panel, “Maximal Starting Repertoire — MSR-5 Overview and Rationale”, 24 June 2021,
https://www.icann.org/en/system/files/files/msr-5-overview-24jun21-en.pdf

[Proposal-Malayalam]

Neo-Brahmi Generation Panel, “Proposal for a Malayalam Script Root Zone Label Generation Ruleset (LGR)”, Updated 26 June 2020,
https://www.icann.org/en/system/files/files/proposal-malayalam-lgr-26jun20-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

[RFC 8228]

A. Freytag, “Guidance on Designing Label Generation Rulesets (LGRs) Supporting Variant Labels”, RFC 8228, August 2017,
https://www.rfc-editor.org/info/rfc8228

[RZ-LGR-5]

Integration Panel, “Root Zone Label Generation Rules (RZ-LGR-5)”, 26 May 2022 (XML),
https://www.icann.org/sites/default/files/lgr/rz-lgr-5-common-26may22-en.xml
non-normative HTML presentation:
https://www.icann.org/sites/default/files/lgr/rz-lgr-5-common-26may22-en.html

[RZ-LGR-3-Mlym]

ICANN, Root Zone Label Generation Rules for the Malayalam Script (und-Mlym), Version 3, 10 July 2019 (XML)
https://www.icann.org/sites/default/files/lgr/lgr-3-malayalam-script-10jul19-en.xml
non-normative HTML presentation:
https://www.icann.org/sites/default/files/lgr/lgr-3-malayalam-script-10jul19-en.html

[RZ-LGR-4-Mlym]

ICANN, Root Zone Label Generation Rules for the Malayalam Script (und-Mlym), Version 4, 5 November 2020 (XML)
https://www.icann.org/sites/default/files/lgr/lgr-4-malayalam-script-05nov20-en.xml
non-normative HTML presentation:
https://www.icann.org/sites/default/files/lgr/lgr-4-malayalam-script-05nov20-en.html

[RZ-LGR-Latin]

“Root Zone Label Generation Rules for the Latin Script”, 26 May 2022,
https://www.icann.org/sites/default/files/lgr/rz-lgr-5-latin-script-26may22-en.xml
non-normative HTML presentation:
https://www.icann.org/sites/default/files/lgr/rz-lgr-5-latin-script-26may22-en.html

[RZ-LGR-5-Overview]

Integration Panel, “Root Zone Label Generation Rules (RZ LGR-5): Overview and Summary”, 26 May 2022,
https://www.icann.org/sites/default/files/lgr/rz-lgr-5-overview-26may22-en.pdf

[Unicode 11.0]

The Unicode Consortium. The Unicode Standard, Version 11.0.0, (Mountain View, CA: The Unicode Consortium, 2018. ISBN 978-1-936213-19-1)
https://www.unicode.org/versions/Unicode11.0.0/

For references consulted particularly in designing the repertoire for the Malayalam script for the Root Zone please see details in the Table of References below. References [0] to [9] refer to the Unicode Standard versions in which the corresponding code points were initially encoded. Reference [106] corresponds to a source given in [Proposal-Malayalam] justifying the inclusion of the corresponding code points. Entries in the table may have multiple source reference values.

Character Classes

Number of named classes	8
Implict defined by script tag	5

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
C	Tag=Consonant	36	{0D15-0D28 0D2A-0D39}		Any consonant
V	Tag=Vowel	13	{0D05-0D0B 0D0E-0D10 0D12-0D14}		Any Malayalam independent vowel
M	Tag=Matra	12	{0D3E-0D43 0D46-0D48 0D4A-0D4B 0D57}		Any Malayalam vowel sign (matra)
H	Tag=Halant	1	{0D4D}		The Malayalam Halant/Virama
B	Tag=Anusvara	1	{0D02}		The Malayalam Anusvara
X	Tag=Visarga	1	{0D03}		The Malayalam Visarga
L	Tag=Chillu	6	{0D7A-0D7F}		Any Malayalam chillu (consonant without any vowel sound)
R	Tag=R	5	{0D46-0D48 0D4A-0D4B}		Any Malayalam reordrant vowel sign
implicit	Tag=sc:Latn	2	{006F 0073}		Any character tagged as Latin
implicit	Tag=sc:Mlym	70	{0D02-0D03 0D05-0D0B 0D0E-0D10 0D12-0D28 0D2A-0D39 0D3E-0D43 0D46-0D48 0D4A-0D4B 0D4D 0D57 0D7A-0D7F}		Any character tagged as Malayalam
implicit	Tag=sc:Mymr	2	{1002 101D}		Any character tagged as Myanmar
implicit	Tag=sc:Orya	1	{0B20}		Any character tagged as Oriya
implicit	Tag=sc:Taml	6	{0B9C 0BAE 0BB5 0BBF 0BC6-0BC7}		Any character tagged as Tamil

Whole label evaluation and context rules

Number of rules	15
Used to trigger actions	3
Used as context rule (C)	7
Used as context rule (V)	4
Anchored context rules	11
Used only in another rule	1

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 ⍟
follows-C-or-0D41	([:C:]|\u0D41)← ⚓︎		✔	C		Section 7, WLE 1: Rule 1: H must be preceded by C or 0D41
follows-C	([:C:])← ⚓︎		✔	C		Section 7, WLE 2: M must be preceded by C
follows-C-V-or-M	([:C:]|[:V:]|[:M:])← ⚓︎		✔	C		Section 7, WLE 3: B must be preceded by C, V or M and WLE 4: X must be preceded by C, V or M
follows-B-X-or-H	([:B:]|[:X:]|[:H:])← ⚓︎		✔	C		Section 7, WLE 5: L cannot be preceded by B, X or H
begins-with-L	(start)[:L:]	✔				Section 7, WLE 6: Label does not begin with L
follows-0D33	(\u0D33)← ⚓︎		✔	C		Section 7, WLE 7. The character ള (0D33) cannot immediately follow ള (0D33), except as part of a defined sequence
follows-0D31	(\u0D31)← ⚓︎		✔	C		Section 7, WLE 8. The character റ (0D31) cannot immediately follow റ (0D31), except as part of a defined sequence
follows-C-L-M-V-and-followed-by-03D1	([:C:]|[:L:]|[:M:]|[:V:])← ⚓︎ →(\u0D31)		✔	C		Section 7, WLE 9: Sequence 0D7B 0D4D must be preceded by C, L, M, V and must be followed by റ (0D31)
reordrant-matra	[:R:]|\u0D4D\u0D30					Reordrant matras, including sequence U+0D4D U+0D30 ( ്ര)
followed-by-R	⚓︎ →((:reordrant-matra:))		✔	V		variant not defined if followed by reordrant matra
followed-by-0D31	⚓︎ →(\u0D31)		✔	V		Section 6.1, V1: A variant is defined when followed by 0D31
follows-0D33-0D4D-or-followed-by-0D4D-0D33-or-R	((\u0D33\u0D4D)← ⚓︎)|(⚓︎ →(\u0D4D\u0D33|(:reordrant-matra:)))		✔	V		Section 6.1, V2: variant not defined if preceded by 0D33+Halant or followed by Halant+0D33 or R
follows-0D31-0D4D-or-followed-by-0D4D-0D31-or-R	((\u0D31\u0D4D)← ⚓︎)|(⚓︎ →(\u0D4D\u0D31|(:reordrant-matra:)))		✔	V		Section 6.1, V3: variant not defined if preceded by 0D31+Halant or followed by Halant+0D31 or R
only-RRA	(start)\u0D31+(end)	✔				Section 7, WLE 10: Labels consisting solely of the letter RRA are disallowed to limit cross-script interaction

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 label matches	begins-with-L	→	invalid		Section 7, WLE 6: Label does not begin with L
3	if label matches	only-RRA	→	invalid		Section 7, WLE 10: Label cannot contain only RRA
4	if at least one variant is in	{out-of-repertoire-var}	→	invalid		any variant label with a code point out of repertoire is invalid ⍟
5	if at least one variant is in	{blocked}	→	blocked		any variant label containing blocked variants is blocked ⍟
6	if each variant is in	{allocatable}	→	allocatable		variant labels with all variants allocatable are allocatable ⍟
7	if any label (catch-all)		→	valid		catch all (default action) ⍟