Are chinese ruby annotations ever start or end aligned?

[r12a]

I assume that all non-zhuyin annotations are centred over the base character(s) they annotate by default. Is that correct, or are there situations where the start of the annotation is aligned with the start of the base text or the end of the base text? (ie. like katatsuki in japanese)

[ethantw]

There is actually a Zhuyin use case for this kind of situation, lol: https://github.com/w3c/clreq/issues/130