for $b in doc("sortieudpipe-3244.xml")/baseudpipe/p
for $c in $b/item
where $c/a[8][contains(text(), 'obj')]
let $gouv := $c/a[7]
let $obj := $c/a[1]
let $num := $obj - $gouv
let $str := if($num>0) then $c/preceding-sibling::*[$num]/a[2]
else($c/following-sibling::*[-$num]/a[2])
let $strobj :=$c/a[2]
return (concat($str," ",$strobj))