How much space around in space-around?

3.3.6.1 Word Alignment
http://w3c.github.io/clreq/#h-word_alignment

When the length of an annotation is shorter than that of its base text, the annotation can be center-aligned (in the case of Western script) or use larger tracking (in the case of Han characters). There are two methods to satisfy the latter, one is to equally distribute the spacing while the other is to align justified.

I assume that for the latter two methods, "equally distribute the spacing" is the equivalent of space-around in CSS, while "align justified" is equivalent to space-between. Is that correct? (see https://www.w3.org/TR/css-ruby-1/#valuedef-ruby-align-ruby-alignspace-between)

If i'm correct, i believe that JLReq prefers space-around to use half the amount of intercharacter space on the outside for space-around, whereas clreq seems to be suggesting a standard amount of space inside and outside the annotation. Is that a correct understanding of how space-around should be implemented for Chinese annnotations?