[basex-talk] Copy Modify Return - base URI preserved?

Dear BaseX people, I just observed that a document obtained by applying Copy/Modify/Return to a source document preserves its base URI, that is, base-uri($resultDoc) = base-uri($sourceDoc). That is marvellous, but can I rely on this as a feature? (In comparison - if I obtained the result document in a "conventional" way by recursive processing of the source document, the base URI would be lost, unless I added an @xml:base.) Kind regards,Hans-Jürgen