Difi, the Norwegian Agency for Public Management and eGovernment, has published a common classification intended to be used in the Norwegian public sector, called Los. It’s specifically aimed at municipal administrations, but could also be used more widely.
Los is published in XTM format, with PSIs for all the main concepts. The main part of it is a hierarchical classification (a taxonomy, basically), but it also has topics (and PSIs) for major governmental units, provinces, counties, and a few other things.
So for anyone developing Topic Maps-based services for the public sector in Norway this is something that should be studied carefully. Given the careful use of PSIs it’s also a major contribution to Open Linked Data in Norway.
Edit: We’ve been asked by non-Norwegian readers where the XTM download is. There’s actually several, and they’re all on the documentation page. The first one, los-alt.xtm, contains everything. The others are subsets.