Hi Hans-Jürgen, The insertion of namespace nodes has not been defined in the XQuery Update spec. You may need choose the classic element constructor for that: let $doc := <doc><a/></doc> return element { node-name($doc) } { $doc/@*, namespace xyz { 'https://basex.org/ns' }, $doc/node() } Hope this helps, Christian ________________________________ Von: Hans-Juergen Rennau via BaseX-Talk <basex-talk@mailman.uni-konstanz.de> Gesendet: Samstag, 2. August 2025 15:51 An: BaseX <basex-talk@mailman.uni-konstanz.de> Betreff: [basex-talk] Add namespace bindings via copy/modify/return Dear BaseX people, I cannot use copy/modify/return in order to add a namespacing: let $doc := <doc><a/></doc> return copy $doc_ := $doc modify insert node namespace xyz {'https://basex.org/ns'} into $doc_ return $doc_ => <doc> <a/> </doc> Is this a bug? Kind regards, Hans-Jürgen