DerivedDimensionDefinition

[eisDNV]

Thank you for a great package.
I am using that to design simulation components where dimensionality and units provide a good help to get things right.
It would be good if I could use derived dimensions instead of the basics, e.g. the dimension [area]:1 instead of [length]:2. I found that at least many of these are defined in default_en.txt, but the registry does not seem to know about them and I could not find a hook to these in the documentation. Do I misunderstand something? How can I access DerivedDimensionDefinitions?