There is an oddity in processing Greek. The combining diacritical perispomenon is not positioned properly, though it appears as it should in the source file. This diacritical is placed properly if one inserts the appropriate character directly.
The PDF file produced by this sample shows the problem as it appears using two different Greek fonts. The first entries in each line are incorrect.
\definefontfamily[mainface][serif][IFAO Grec Unicode]
\setupbodyfont[mainface, 24pt]
\definefont[HellenicaCU][file:HellenicaCU.ttf at 24pt]
\starttext
αῖ %combining diacritical
αῖ %char 1FD6
\HellenicaCU{
αῖ %combining diacritical
αῖ %char 1FD6
}
\stoptext
As I review my files, I see that this is a fairly recent problem, though I cannot say exactly when it first occurred.
The other combining diacriticals process as they should.
Alan