How does line start/end overflow work for romanised phonetic annotations?

The following is my understanding of the jLReq rules for dealing with situations where an annotation would otherwise protrude outside a line start or end. Are the Chinese rules the same or different? (In either case, it would be useful to say something in cLReq, i think.)

Is the annotation longer than the base text?
NO There’s no problem to solve here. Stop.
YES Carry on.

Is the annotation wanting to extend beyond the line start or end?
NO You need to use rules about overhang, rather than these. Stop.
YES Carry on.

You have two choices:

1. FLUSH Both annotation and base are aligned with line end. The annotation is aligned with the start of the base (katatsuke).
   

2. OFFSET The base is moved away from the line end. The annotation is aligned with the middle of the base (nakatsuke).
   

In either case, the bit of the annotation that overflows the base on the inside of the line will need to be positioned relative to the adjacent base characters using the rules for overhang (which are described elsewhere).

Did you choose FLUSH when there are multiple base characters for the annotation (ie. group ruby)?
NO You’re ok. Stop.
YES You should spread out the base characters, using equal amounts of space.