Are node-types CSV files required or optional?

[alex4200]

In the documentation for the sonata specs in the section Representing nodes it is unclear if the "node types CSV files" are required or optional. Because it says:

In the case a node attribute is defined in both the node types CSV and the nodes HDF5, the value in the nodes HDF5 overrides the node types CSV value.

So if the HDF5 files contain the node types, the CSV files are not required.

However when trying to read a HDF5 file with pysonata using sonata.circuit.File it seems that a CSV file is required.

I appreciate if this can be clarified and/or fixed.