There is in fact a similar case in biblical Hebrew, which will need to be dealt with at some time, and perhaps should be dealt with soon as part of a comprehensive review of ancient Hebrew support.There's an interesting case with the <Greek Dialytika and Tonos> precomposed combining character <U+0344>. Its canonical decomposition is <U+0308, U+0301>, and it is excluded from canonical recomposition (so it is really a *compatibility character* that should not be present in any normalized form).
However, its canonical decomposition into <COMBINING DIERESIS, COMBINING ACUTE ACCENT> who are both of combining class 230 (Above), has an impact in renderers: they are supposed to stack one above the other, so the ACUTE ACCENT (oxia, tonos) should appear *above* the DIERESIS (Dialytika). But usage in Greek (similar cases occur with Vietnamese Latin letters with two above diacritics), show that they do not stack up, but above diacritics are really combined (the tonos accent is written in the middle of the two dots of the dialitika).
The hataf vowels in Hebrew, 05B1-05B3, are graphically combinations of sheva, 05B0, and other vowels, though they have correctly not been given decompositions as such. When these hataf vowels occur together (on the same base letter) with meteg, 05BD (a small vertical line), meteg can be placed to the right or to the left of the hataf vowel, but is most frequently positioned in the middle of the vowel, between its two elements, so as a kind of ligature.
Meteg usually occurs to the left of other low positioned vowels, sometimes to the right. So it is appropriate that the canonical ordering is always vowel - meteg. The relatively few occasions when it occurs to the right provide another good use of CGJ, so that this combination can be encoded meteg - CGJ - vowel.
But what should be done when meteg is expected to be in the middle? One thought was to encode hataf_vowel - CGJ - meteg, but this is not suitable if CGJ is not supposed to promote ligation. Perhaps it is better to note that with the hataf vowels the ligature is the default, and so expect hataf_vowel - meteg to be rendered as the ligature. Then in the relatively few cases where the ligation is not required CGJ can be inserted, i.e. hataf_vowel - CGJ - meteg, to suppress the ligation. Is this is a valid use of CGJ?
-- Peter Kirk [EMAIL PROTECTED] http://web.onetel.net.uk/~peterkirk/
