User-defined Function in Xquery??

Is it possible to define an user function in Tamino via Xquery?? i know that Xquery has this possibility but i didnt find whether Tamino supports that.
Thanks in regards

Hello Martin,
Currently Tamino’s implementation of XQuery does not include support for User-Defined Functions. The implementation status is documented in the Tamino Server Documentation/XQuery 4 User Guide/Implementation Status.

However, the next version of Tamino will support user defined functions in XQuery. In Tamino 4.2 and earlier, you can have user defined functions via server extensions