How may we precisely position 4 glyphs as in the Sanskrit word हरिः॑ ?
1. There is a Base glyph Unicode $0930 = र
2. There is a Matra glyph Unicode $093F = ि
3. There is a Visarga glyph Unicode $0903 = ः
4. There is a double Svarita glyph Unicode $1CDA (or the stress sign Udatta $0951)
to make the final form without intersecting the matra glyph, e.g. रिः॑
We are unable to do it using abvm mark-to-base anchors.
Just positioning 3 glyphs works, e.g. रि॑ = Base glyph + Matra glyph + double Svarita glyph.