> select="*/tbody/row[position() mod $grp-size=1].
> 
> And this expression looks a little fishy since $grp-size=1 
> will return a boolean value which is probably not a 
> meaningful argument for "mod".
> 

Eliot's other comments are all valid but this one's wrong, I think. The
"mod" operator has higher precedence than "=". Mind you, it would probably
be worth writing it as 

[(position() mod $grp-size) = 1]

so that other people reading your code don't make the same mistake.

Michael Kay
http://www.saxonica.com/