O-class is not an advertised class on SK, but it is apparently still used for Military Fares on Domestic Norwegian routes. I got an E-ticket today for my first trip for the Army since 2002. Fare Class is listed as O First. Of course, First class does not exist on DOM NO. SKBU are running a LCC operation when it comes to inflight service in any case, but in the SK database O apparently loads as First, not Economy.

When earning of miles/points still was possible on DOM NO Military O-class earned as business/full fare: 1200 EB points per segment.