Grapheme clusters fail to represent syllabic conjuncts #62

The Unicode concept of 'grapheme cluster' currently fails to represent syllabic conjuncts (plus vowels, etc) in scripts like Bengali. Bengali is even more complex in this regards because it requires Ya-Phalaa after vowel which is formed by Vowel followed by Viaram(Hasant) and consonant combination, therefore breaking the basic notion of Akshar formation to represent the glyph(Ya-Phalaa/Ja-Phalaa). This means that various editing operations, line breaking algorithms, vertical text, etc. are likely to break text at the wrong point.

Indic Layout Requirements provides a grammar for indian orthographic syllable boundaries which works for Bengali, and CSS uses the concept of 'typographic character unit', rather than grapheme cluster, in its specs with the explanation that these cases are beyond the scope of the grapheme cluster concept and that implementations should provide appropriate support. In addition, a modification to the concept of grapheme cluster is currently in development at the Unicode Consortium, which is likely to resolve the problem for a script like Bengali.

See requirements at: Indic Layout Requirements