for $b in doc("sortieudpipe-3244.xml")/baseudpipe/p
for $c in $b/item
where $c/a[8][contains(text(), 'subj')]
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[3]
else($c/following-sibling::*[-$num]/a[3])
let $strsub :=$c/a[3]
return (concat($str," [",$c/a[8],"] ",$strsub))