The international categories A, B, C, D and E are largely the same as when they were introduced in Norway in 1979. Categories A1 (light motorcycle), C1 (light lorry) and D1 (minibus) were introduced in 1997. Categories AM (moped) and A2 (medium-sized motorcycle) were introduced in January 2013.
If your driving licence was issued before 2005, you may have additional driving entitlements than if your driving licence was issued in or after 2005..
If you exchange your driving licence for a new one today, the additional entitlements will be added to the new driving licence in the form of national numeric codes, and by checking the national driving licence categories for snowmobiles (S) and tractors (T).
The national categories and codes apply to driving in Norway, and they may not be valid abroad.
The current rules are described in the Driving Licence Regulations (Lovdata, in Norwegian).