[MPEG-OTSPEC] Why no GPOS10?

[Simon Cozens]

On 02/08/2020 16:47, Simon Cozens wrote:
> This would allow for moving consecutive nukta marks rightwards while being sure they don’t conflict with other marks to their right.
> If that’s unclear (or you’re not convinced this solves a problem that can’t be dealt with other ways) I’ll try and hack up an example and implementation in Harfbuzz.

Huh. Having now actually implemented this, I can see that I'm wrong. :-)

Whereas substitution can have a "knock-on effect" on future rules 
because it changes the glyph stream and so can change the effect of 
future substitution rules, positioning adjustments have no cumulative 
effects; they're essentially stateless, so it doesn't matter which order 
you do them in.

Oh well, back to the drawing board...