In a, position() is 1 and last() is 2 In b number 1, $a.pos=1 and $a.last=2 In b number 2, $a.pos=1 and $a.last=2 In a, position() is 2 and last() is 2 In b number 1, $a.pos=2 and $a.last=2 In b number 2, $a.pos=2 and $a.last=2 In b number 3, $a.pos=2 and $a.last=2