> > Use count(distinct-values(/test/row/string(transition)))
>
> I would use the more obvious and self-explanatory:
>
> let $test := /test/row
>   return
>      count(distinct-values($test/transition)) + 1[$test[not(transition)]]
>

Actually, that's not equivalent. My solution (using string()) treats an empty
transition element and an absent transition element as equivalent; DImitre's
solution treats them as distinct.

Michael Kay
Saxonica