+<stations>
+{
+for $doc in ('stations.qpl')
+for $station in doc($doc)//station,
+ $stationcode in doc('stationcodes.qpl')//station[name = $station/name]
+return
+<station>
+{$station/name}
+{$station/pos}
+{$stationcode/code}
+</station>
+}
+{
+for $doc in ('stations.qpl')
+for $station in doc($doc)//station
+let $stationcode := doc('stationcodes.qpl')//station[name != $station/name]
+where
+$station/name != $stationcode/name
+return
+<station>
+{$station/name}
+{$station/pos}
+</station>
+}
+</stations>