declare copy-namespaces preserve, no-inherit;
declare boundary-space preserve;
copy $data :=
modify
insert node
into $data
return
let $w := $data/w
let $x := $w/x
let $y := $x/y
let $z := $y/z
return
{namespace-uri-for-prefix("a", $w), namespace-uri-for-prefix("b",$w)}
{namespace-uri-for-prefix("a", $x), namespace-uri-for-prefix("b",$x)}
{namespace-uri-for-prefix("a", $y), namespace-uri-for-prefix("b",$y)}
{namespace-uri-for-prefix("a", $z), namespace-uri-for-prefix("b",$z)}