@millihertz @rk hmm, i'm not sure, but. A state machine is useful (for attaching marks, and modifying the shapes of glyphs in arabic, and potential in Hangeul (although i don't think anyone does it like that)). And if you _start_ from that position, it could be somewhat simpler than the current mess. The OpenType Layout "state machine" is not good enough (can't swap glyphs, basically), but apparently the Apple Advanced Typography one is. But it's been deprecated for ages. But it suggests a path to potentially better territory.