I checked the helppatches in lib/vlCore the grey book but still had troubles deserializing my custom datatype. maybe a extra example in lib/vlcore would help others. Took me a long time to figure out that I had to split the xElement to get a spread of my elements.
Deserialize node works, but behaves in a strange way when connected directly to the xElement node. It was not clear to me that I had been working with the wrong datatype.