Controls needed to adjust diacritic positioning

[r12a]

For advanced typographic purposes, the fixed position of diacritical marks relative to base letter or baseline and the logical stacking behavior of them might not be sufficient. Therefore, it should be possible to adjust the positioning and combining order and changes to the individual marks when combining. Fonts and other systems may implement the logic needed to result in an optimal presentation of diacritical mark clusters by default.

[r12a]

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