Consider deleting the "officialStatistics" root concept, or typing it as an ActivityArea

[tfrancart]

The description of GAMSO reads:

At the top of the scheme, an instance of ActivityCategory represents the whole activity of statistical organizations and is named officialStatistics.

This is inconsistent with the fact that, below this root, we find instances of ActivityAreas. Making this root an ActivityCategory entails that it can be selected as a value to type an Activity, whereas its children concepts cannot (see #111).

I would advise to simply delete this root concept as it is not useful, and keep the ActivityAreas collections as the entry points to the taxonomy. If you absolutely want to keep it, then it should be typed ActivityArea for consistency.