Label Generation Rules for the Malayalam Script

Overview

This document specifies a set of Label Generation Rules (LGR) for the Malayalam script for the second level domain or domains identified above. The starting point for the development of this LGR can be found in the related Root Zone LGR [RZ-LGR-Mlym]. The format of this file follows [RFC 7940]. This LGR is adapted from the “Reference LGR for the Second Level for the Malayalam Script” [Ref-LGR-und-Mlym], for details, see Change History below.

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

Repertoire

The repertoire contains 70 code points for letters used in the Malayalam language in addition to ten sequences used in defining variants. The repertoire is a subset of [Unicode 11.0.0]. For details, see Section 5, “Repertoire” in [Proposal-Malayalam]. (The proposal cited has been adopted for the Malayalam 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, plus U+002D - HYPHEN-MINUS, for a total of 91 repertoire elements.

Any code points outside the Malayalam Script repertoire that are targets for out-of-repertoire variants would be included here only if the variant is listed in this file. In this case they are identified as a reflexive (identity) variant of type “out-of-repertoire-var”. Whether or not they are listed, they do not form part of the repertoire.

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.

Variants

The variants defined in this LGR are limited to those required for use in zones not shared with any other script. As such, this LGR does not define cross-script variants. However, using this LGR concurrently with any LGR for Tamil, Oriya, and Myanmar in the same zone will create potential cross-script issues. For details, see Section 6, “Variants” in [Proposal-Malayalam]. Mitigation of these cross-script variants can be addressed by using the Common LGR. For details, see Section 3, “Use of Multiple Reference LGRs in the Same Zone” in [Level-2-Overview]. In addition to variants defined by this LGR, the full variant information related to this script and added by concurrent use with the Tamil, Oriya, and Myanmar LGR(s) can be found in the following LGRs: [Ref-LGR-Tamil-Full-Variant-Script] and [Ref-LGR-Myanmar-Full-Variant-Script].

This LGR defines in-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.

Digit Variants: The Malayalam reference LGR does not include native digits, so there are no semantic variants defined.

By transitivity, all ASCII digits are semantic variants of any cross-script native digits. Any Malayalam label that is otherwise a cross-script variant of a label in another script, will remain a variant if both labels add digits of the same value in the same position, irrespective of whether they are ASCII digits or (in the case of the other script) native digits.

However, some Malayalam letters are homoglyphs of Malayalam native digits. For example, U+0D6A ൪ MALAYALAM DIGIT FOUR and U+0D6F ൯ MALAYALAM DIGIT NINE are homoglyphs of U+0D7C ർ MALAYALAM CHILLU RR and U+0D7D ൽ MALAYALAM CHILLU N respectively.

Should an extension be contemplated that adds native digits, these might require variant relations. At the same time, however, any native digits would normally be semantic variants of the ASCII digits. In any zone containing multiple scripts, these two types of variant relation for digits may lead to complication once transitivity is applied.

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.

In other cases, the sequences or code points making up source and target are constrained by explicit context rules on the code points (or by implicit context rules defined for the adjacent code points). In such a case, any variants may require context rules that match the intersection between the effective 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. Symmetry requires the same context rule for both forward and reverse mappings.

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 would be delegated, while any other equivalent labels should be blocked. There is no preference among these labels.

This LGR does not define allocatable variants.

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

Character Classes

The basic characters in Malayalam are classified here into the following categories: Consonants, Vowels, Matra and Reordrant Vowel Diacritics, Halant, Visargam, Anusvaram 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].

Anusvaram: 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].

Visargam: 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

Common Rules

By default, the LGR includes the rules and actions to implement the following restrictions mandated by the IDNA protocol. They are marked with ⍟.

• Hyphen Restrictions — restrictions on the allowable placement of hyphens (no leading/ending hyphen and no hyphen in positions 3 and 4). These restrictions are described in Section 4.2.3.1 of RFC 5891 [150]. They are implemented here as context rule on U+002D (-) HYPHEN-MINUS.
• Leading Combining Marks — restrictions on the allowable placement of combining marks (no leading combining mark). This rule is described in Section 4.2.3.2 of RFC 5891 [150].

Default Actions

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

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  ു  VOWEL SIGN U
• 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 RRA and U+0D31 റ LLA 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 RRA

The following context rules apply to variants:

• V1: A variant is defined when followed by U+0D31 റ
• V2: A variant preceded by U+0D33 ള + Halant or followed by R or Halant + U+0D33 ള is not defined
• V3: A variant preceded by U+0D31 റ + Halant or followed by R or Halant + U+0D31 റ 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 U+0D31 റ RRA would overlap with the various variant sequences beginning with 0D31, therefore this LGR drops the U+0D31 റ from the end of these sequences, but adds context rule V1, when="followed-by-0D31" instead. Because all the variants also end in U+0D31 റ, 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 LGR in this document has been adapted from the corresponding Reference LGR for the Second Level. The Second Level Reference LGR for the Malayalam Script was developed by Michel Suignard and Asmus Freytag, based on the Root Zone LGR for the Malayalam script and information contained or referenced therein; see [RZ-LGR-Mlym]. Suitable extensions for the second level have been applied according to the [Guidelines] and with community input. The original proposal for a Root Zone LGR for the Malayalam script, that this reference LGR is based on, was developed by the Neo-Brahmi Generation Panel (NBGP). For more information on methodology and contributors to the underlying Root Zone LGR, see Sections 4 and 8 in [Proposal-Malayalam], as well as [RZ-LGR-Overview].

Changes from Version Dated 15 December 2020

Unicode Version has been updated.

Changes from Version Dated 25 October 2024

This version modifies the Second Level Reference LGR for the Malayalam Script [Ref-LGR-und-Mlym] by injecting the complete (maximal) set of cross-repertoire variants, including any imposed by transitivity. Injected variants are marked by special comments. Any character classes, context and WLE rules required for testing are also imported. In all other respects, description or annotations have not been updated to reflect the injected variants. Any LGR elements that might pose a possible conflict when the LGR is used with the Common LGR for cross-repertoire variant resolution are clearly marked. All modifications are carried out mechanically; there may be an occasional context rule or similar that is injected because its definition relates to some repertoire element even though it can never be triggered by any label valid under the modified LGR.

References

The following general references are cited in this document:

[Guidelines]

ICANN, “Guidelines for Developing Reference LGRs for the Second Level”, (Los Angeles, California: ICANN, 27 May 2020),
https://www.icann.org/en/system/files/files/lgr-guidelines-second-level-27may20-en.pdf

[Level-2-Overview]

Internet Corporation for Assigned Names and Numbers, (ICANN),“Reference Label Generation Rules (LGR) for the Second Level: Overview and Summary” (PDF), (Los Angeles, California: ICANN, 25 October 2024),
https://www.icann.org/en/system/files/files/level2-lgr-overview-summary-25oct24-en.pdf

[Proposal-Malayalam]

Neo-Brahmi Generation Panel, “Proposal for a Malayalam Script Root Zone Label Generation Ruleset (LGR)”, 7 May 2020,
https://www.icann.org/en/system/files/files/proposal-malayalam-lgr-07may19-en.pdf

[Ref-LGR-und-Mlym]

ICANN, Second Level Reference Label Generation Rules for the Malayalam Script (und-Mlym), 25 October 2024 (XML)
https://www.icann.org/sites/default/files/packages/lgr/lgr-second-level-malayalam-script-25oct24-en.xml
non-normative HTML presentation:
https://www.icann.org/sites/default/files/packages/lgr/lgr-second-level-malayalam-script-25oct24-en.html

[Ref-LGR-Myanmar-Full-Variant-Script]

ICANN, Second Level Reference Label Generation Rules for the Myanmar Script (und-Mymr), 25 October 2024 (XML)
https://www.icann.org/sites/default/files/packages/lgr/lgr-second-level-myanmar-full-variant-script-25oct24-en.xml
non-normative HTML presentation:
https://www.icann.org/sites/default/files/packages/lgr/lgr-second-level-myanmar-full-variant-script-25oct24-en.html

[Ref-LGR-Tamil-Full-Variant-Script]

ICANN, Second Level Reference Label Generation Rules for the Tamil Script (und-Taml), 25 October 2024 (XML)
https://www.icann.org/sites/default/files/packages/lgr/lgr-second-level-tamil-full-variant-script-25oct24-en.xml
non-normative HTML presentation:
https://www.icann.org/sites/default/files/packages/lgr/lgr-second-level-tamil-full-variant-script-25oct24-en.html

[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-Mlym]

ICANN, Root Zone Label Generation Rules for the Malayalam Script (und-Mlym), 26 May 2022 (XML)
https://www.icann.org/sites/default/files/lgr/rz-lgr-5-malayalam-script-26may22-en.xml

[RZ-LGR-Overview]

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

[Unicode 11.0.0]

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 second level 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. In the listing of whole label evaluation and context rules, reference [150] indicates the source for common rules.