OK, thanks, I think it might. I'll mull it over.
>
> following has context node a for position(), but beware, it is in the
> third predicate, so it counts only the subset selected by the earlier
> predicates.
> a[count(b/c/*) = '12'][b[@x = 'rr']][position() = 2]
>
>
> HTH,
>
> -- Abel Braaksma