Hi Joachim,
Here is a post about reading xml files: https://gdl.graphisoft.com/tips-and-tricks/how-to-use-the-gdl-xml-add-on/ In this sample you can check moving to a node with a name – so I think that you can jump to a product node, and check the ID in different steps. There is an example for getting the info from CDATA too.
Gergely Fehér
Team Leader, Library Team
GRAPHISOFT SE