L2/10-056 Title: Updated property classification for Brahmi-derived scripts. Date: 2010-02-02 Author: Ken Whistler Action: For consideration by the UTC The following information accompanies the suggested provisional data files, IndicProps.txt, and fills out the information about the metaproperties for each suggested provisional property. 1. Indic_Syllabic_Category The major enumerated type for the structural parts of Indic syllables, or more properly aksaras. Name: Indic_Syllabic_Category Abbreviated Name: isc Aliases: Type: enumerated Class: attribute Scope of Use: Display, Segmentation Data Type: enumerated_symbol Data Type Range: (see enumeration) Actual enumeration of the values: Indic_Syllabic_Category = [bindi, visarga, avagraha, nukta, virama, vowel_independent, vowel_dependent, vowel, consonant_placeholder, consonant, consonant_dead, consonant_repha, consonant_subjoined, consonant_medial, consonant_final, consonant_head_letter, diacritic_letter, tone_letter, tone_mark, register_shifter, other] Number of values: 21 Closed: No Devault value: other Max value: n/a Code Point: No Status: Provisional Derivational Status: Mixed Primary Status: True Overridable: True Stability: N/A (not immutable or fixed) Obsolete: No Deprecated: No Stabilized: No XML Schema Id: TBD Documentation File: IndicProps.txt Documentation Location: Chapters 9, 10, primarily Age: 6.0 The value isc=other could just be the default value for all other characters which didn't fit into one of the specifically Indic script types, including vowels and consonants in non-Indic scripts. The Indic_Syllabic_Category alone wouldn't be enough to define aksaras, as you would need to include various diacritic marks, for example -- but those would depend on other, already-defined properties. I see Indic_Syllabic_Category as only supplying the additional information not derivable from other properties. ====================================================================== A possible additional property would identify the liquids and nasals subject to special behavior in aksaras in many Brahmi-derived scripts: Consonant_Join_Group = [nga, ya, ra, la, wa, ha, other] The point of this second alternative property would not be to claim that these are all important for every script -- but identifying each of these clearly for each Brahmi-derived script that contains an analog would pretty much cover the ground in terms of truly exceptional behavior. At least it is worth taking a first look at, to see if we can actually define this for all the Brahmi-derived scripts. ======================================================================= 2. Matra_Placement For matras specifically, a placement property. Name: Matra_Placement Abbreviated Name: mp Aliases: Type: enumerated Class: attribute Scope of Use: Display, Segmentation Data Type: enumerated_symbol Data Type Range: (see enumeration) Actual enumeration of the values: Matra_Placement = [Right, Left, Left_And_Right, Top, Bottom, Top_And_Bottom, Top_And_Right, Top_And_Left, Top_And_Left_And_Right, Bottom_And_Right, Top_And_Bottom_And_Right, Overstruck, None] Of those, Bottom, Top, Bottom_And_Top, and Overstruck would be gc=Mn, while the other values would correspond to gc=Mc. Overstruck is for Kharoshthi vowels. Placement types involving "Left" all require a glyphic reordering from logical order during layout. Number of values: 13 Closed: No Devault value: None Max value: n/a Code Point: No Status: Provisional Derivational Status: Simple Primary Status: True Overridable: True Stability: N/A (not immutable or fixed) Obsolete: No Deprecated: No Stabilized: No XML Schema Id: TBD Documentation File: IndicProps.txt Documentation Location: Chapters 9, 10, primarily Age: 6.0 ==================================================================== 3. Danda And then, for the dandas, a binary property: Danda = True/False Status: Provisional Derivational Status: Simple Primary Status: True Overridable: True Stability: N/A (not immutable or fixed) Obsolete: No Deprecated: No Stabilized: No XML Schema Id: TBD Documentation File: IndicProps.txt Documentation Location: Chapters 9, 10, primarily Age: 6.0 ===================================================== Examples of Consonant_Join_Group for Devanagari: [Not derivable] NGA 0919;DEVANAGARI LETTER NGA;Lo;0;L;;;;;N;;;;; YA 092F;DEVANAGARI LETTER YA;Lo;0;L;;;;;N;;;;; RA 0930;DEVANAGARI LETTER RA;Lo;0;L;;;;;N;;;;; LA 0932;DEVANAGARI LETTER LA;Lo;0;L;;;;;N;;;;; WA 0935;DEVANAGARI LETTER VA;Lo;0;L;;;;;N;;;;; HA 0939;DEVANAGARI LETTER HA;Lo;0;L;;;;;N;;;;;