This is a unique problem because this is probably the only case where the same script produces conjuncts for one language and not for another. I had asked for a separate Tamil Brahmi virama to be encoded which would obviate this problem but that was shot down. Maybe that case should be reopened?
On Sat 21 Jul, 2018, 06:33 Richard Wordingham via Unicode, < [email protected]> wrote: > A problem has been spotted with the rendering of Tamil Brahmi vowels - > in particular the sequence <U+11013 BRAHMI LETTER KA, U+11044 BRAHMI > VOWEL SIGN O, U+11046 BRAHMI VIRAMA> does not conform to the grammar > of the Universal Shaping Engine (USE); a dotted circle may be inserted > between the vowel and the pulli. > > When considering font-level remedies, I realised that there may be a > problem with a following consonant - is <U+11013, U+11044, U+11046, > U+11022 BRAHMI LETTER TA> a correct encoding of what may be > transliterated as _kŏta_? > > The nearest to a convincing justification I can find for it to require > U+200C ZWNJ after the virama is the text in TUS Section 12.1 for > *Explicit Virama*, but that merely says that ZWNJ is required to > produce explicit virama rather than a _conjunct_. As I understand > it, a subscript final consonant would be encoded as consonant+virama > rather than virama+consonant, so there is no ambiguity in Brahmi text. > (If we try to make a rule out of two conflicting mechanisms, the > difference might be that one is used for viramas and the other is used > for invisible stackers, though that would require changing U+10A3F > KHAROSHTHI VIRAMA back to being a virama.) The problem is that a font > that tries to recover the situation might interpret <U+11013, > U+11044, U+25CC DOTTED CIRCLE, U+11046, U+11022> as having TA > subscripted to the dotted circle. If ZWNJ is required for _kŏta_, what > text if any in TUS requires it? > > Richard. > >
