Generally, I flatten the register when I want to access the subfields. To flatten a register, create a Selection view and in the “Output” tab of the view, right-click on the register and click Project subfields of…
For more details, you can refer to the [Creating Flatten Views](https://community.denodo.com/docs/html/browse/8.0/en/vdp/administration/creating_derived_views/creating_flatten_views/creating_flatten_views) section of the Virtual DataPort Administration Guide.
If you still need help and if you are a valid Support User, you may open a Support Case at the Denodo Support Site and the Support Team will help you.
Hope this helps!