This file contains Label Generation Rules (LGR) for the Greek script for the Root Zone. For more details on this LGR and its development, see "Proposal for a Greek Script Root Zone Label Generation Ruleset (LGR)" [Proposal-Greek]. The format of this file follows [RFC 7940].
The Root Zone LGR for the Greek script lists 36 unique code points. The repertoire includes code points used by the modern day Greek language, which is the official language of Greece and Cyprus. The repertoire also covers the Pomak language, which is the only “non-Greek” language that uses Greek characters nowadays. For more details, see Section 5 "Repertoire" in [Proposal-Greek]).
The repertoire is based on [MSR-4], which is a subset of Unicode 6.3 [Unicode 6.3]. No Greek code points from MSR-4 have been excluded.
According to Section 6 “Variants”, in [Proposal-Greek], this LGR defines the following categories of variants:
Vowels without tonos and/or diaeresis are treated as allocatable in-script variants of their forms without tonos and/or dialytika. The variants in the opposite direction and between forms with tonos and dialytika, for example, are of type "blocked". To reduce the number of allocatable labels in case the applied-for label contains multiple vowels with diacritics, the LGR defines special variant types and actions so that only two allocatable variants are allowed for each label: the label as applied-for (original label), and the label with all unaccented vowels (base forms). Note that this restriction is independent of the restriction on variants of sigma, see below, so that a total of up to four allocatable labels may exist.
For more details, see Section 6.1.2 in [Proposal-Greek]).
‘Sigma’ is the 18th character of the Greek alphabet, corresponding to /s/. There are two forms of lower case sigma: U+03C3 GREEK SMALL LETTER SIGNM and U+03C2 GREEK SMALL LETTER FINAL SIGMA. The final sigma is used instead of the lower case sigma at the end of words, but it may also occur at other points of a label. The lower case sigma is treated as an allocatable in-script variant of the final sigma, but not in the reverse. To reduce the number of allocatable labels in case the applied-for label contains multiple final sigmas, the LGR defines special variant types and actions so that only two allocatable variants are allowed for each label: the label as applied-for (original label), and the label with only regular sigmas. Note that this restriction is independent of the restriction on variants of vowels, see above, so that a total of up to four allocatable labels may exist.
For more details, see Section 6.1.3 in [Proposal-Greek]).
Code points for the accented forms of vowels have been given a reflexive variant type of "r-diac". The code point for the final form has been given the reflexive variant type "r-final". (By convention, the prefix “r-“ marks a type used in a reflexive variant mapping, that is, it represents an instance of the original code point at that location in a variant label, see Section 5.3.4 in [RFC 7940].)
Variant mappings to the base forms of vowels are of type "base" and the variant mapping to the nonfinal form of sigma is of type "nonfinal". Special <action> elements defined for this LGR use these types to ensure the following restrictions. (See also "Greek-specific Actions" below.)
As result of these actions, any label as applied for may result in at most four allocatable labels, however, if it is applied for without diacritics or final sigmas it will not result in any allocatable variant labels.
Cross-script variants are defined based on "identical" appearance. Such out-of-repertoire variants are defined with a comment "Cross-script homoglyph" or "Cross-script near homoglyph". The largest number of such variants are with the related scripts, Armenian, Cyrillic and Latin, but a few simple letter shapes also may have correspondence with those in less related scripts.
For more details, see Section 6.1.4 in [Proposal-Greek]).
This LGR inherits additional blocked cross-script variants by integration; they may not be listed here unless they result in in-script variants. However, for consistency, the variant mappings among the related scripts Armenian, Cyrillic, Greek and Latin are listed in full. 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 LGR defines no character classes.
The LGR includes the set of required default WLE rules and actions applicable to the Root Zone and defined in [MSR-4]. They are marked with ⍟.
This LGR does not define Greek-specific Whole Label Evaluation Rules.
The LGR includes the set of required default actions applicable to the Root Zone and defined in [MSR-4]. They are marked with ⍟.
The LGR contains additional Greek-specific actions as described in Section [TBD], "[TBD]" of [Proposal-Greek]. These resolve the extended set of variant types into a disposition for variant labels of either "allocatable" or "blocked". Greek-specific actions that are triggered by the LGR-specific variant types described above limit the "allocatable" variant labels to those containing only unaccented vowel or nonfinal sigma variants or both, while disallowing mixed use of accented and unaccented vowels or final and non-final sigma, except as in the original applied-for label. To account for original labels, reflexive variant mappings with an "r-" prefix are used. (See [RFC 7940]).
Note that variant mapping types are not symmetric: they depend on which code point is considered the source or the target in a given mapping. As specified in [RFC 7940], mapping types are evaluated for each permutation of a label and its variants, with code points that are unchanged in a given label given the type of their "reflexive" mapping. The actions finally evaluate the collected set of mapping types and resolve them into one of two dispositions for the variant label. Per [RFC 7940] actions are always applied one after the other, and the evaluation stops at the first action that assigns a disposition to a given label.
For more information on how to assign a variant label disposition under this LGR, see Section 8, "Designing Dispositions and Whole Label Evaluation Rules (WLE)" in [Proposal-Greek]. The specification of variants in the LGR follows the guidelines in [RFC 8228].
The Root Zone LGR for the Greek script was developed by the Greek Generation Panel. The process followed by the Panel was according to work plan given in “Proposal for the Generation Panel for the Greek Script Label Generation Ruleset for the Root Zone”. For additional detail on methodology and contributors see Sections 4 and 8 in [Proposal-Greek].
The following general references are cited in this document:
For references consulted particularly in designing the repertoire for the Greek script for the Root Zone please see details in the Table of References below. Reference [0] refers to the Unicode Standard version in which corresponding code points were initially encoded. Reference [100] , corresponds to the source given in [Proposal-Greek] for justifying the inclusion of the corresponding code points. Single code point or ranges may have multiple source reference values.
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