Okay, this is slightly complicated, but when the attached Glyphs File
MarkMarkTest.glyphs.gz (a subset of Noto Sans Tagalog) is compiled with fontmake, the resulting feature file looks like this:
Notice that we have mark-to-base and mark-to-marks rule in the Tagalog part of the font that goes through the abvm feature, but we only have mark-to-base, and no mark-to-mark, for the dotted circle bit, leading to:
Okay, this is slightly complicated, but when the attached Glyphs File MarkMarkTest.glyphs.gz (a subset of Noto Sans Tagalog) is compiled with fontmake, the resulting feature file looks like this:
Notice that we have mark-to-base and mark-to-marks rule in the Tagalog part of the font that goes through the
abvm
feature, but we only have mark-to-base, and no mark-to-mark, for the dotted circle bit, leading to:I think there should be a
mkmk
feature produced as well.