They are split into four pools (labelled A-D) of three according to their past performance. Each team plays three matches against three teams of other pool (pool A plays against pool D and pool B plays against pool C).
The teams are separated into four categories (A-D) consisting of three, determined by their previous success. In each round, a team plays against three opponents from a different category (category A competes with category D, while category B clashes with category C).