for $adj in //element/data[@type='type']
let $texta := $adj/following-sibling::data[@type='string']/text()

let $nom := $adj/parent::element/following-sibling::element[1]/data[@type='type']
let $textn := $nom/following-sibling::data[@type='string']/text()

return if($adj/text()='ADJ' and $nom/text()='NOM')
then string-join(($texta, $textn), ' ')
else ()