How to display extra base text/ruby text in <ruby>?

[vickyhan618]

There is a 28 steps algorithm described in https://html.spec.whatwg.org/multipage/text-level-semantics.html#the-ruby-element

When ruby base and ruby text is not 1:1 matching, how to display extra ruby base text and ruby text?
I got some examples, and I followed the algorithm step by step. After I get the output, I still don't know how to display. I also noticed chrome and firefox have different behavior(chrome drop the extra ruby text to normal text, firefox display it on top).

Case1: 2 rb with 1 rt
e.g. "遼りょうとう東"

Output: base text segment: {[0,1)}
Annotation segment: {[1,2)}
Ignored segment: {[2,3)}
Associate [0,1) -> [1,2)
=> "東' seems is treated as ignored segment basing on the algorithm, however text says "Ignored segments do not form part of the document's semantics". That seems to contradict the algorithm? How to display ignored segment?

Case2: empty rt/rt occurs first, "Aaa"
start index is only set at step 12. But if the first rt is empty, we will jump from 11 to 18, and start index is always null. When to update start index?

Another doubt, in steps for "set the current base text", item 2 says "...described by the range annotation range." I don't see that "annotation range" is defined, and I suspect they meant "...described by the range text?