The formation of an Opposition at the NI Assembly: what does it mean?

http://www.stratagem-ni.com/latest/2016/may/opposition-what-does-it-mean

Good article from the folks at Stratagem:

With the UUP announcing that they are set to form a formal opposition in the Northern Ireland Assembly, we take a look at what the practicalities are for them as set out in the Assembly and Executive Reform (Assembly Opposition) Act (Northern Ireland) 2016.

Who can form the official Opposition in the Assembly?

The Opposition can be formed by one or more qualifying parties in the Assembly. A qualifying party, essentially, is a party which has chosen not to hold a Ministerial office despite being entitled to do so under Assembly rules. A qualifying party may also be a party whose members comprise 8 per cent or more of the total number of seats in the Assembly (108), and does not contain a member who is a Minister.