"1st phase": 4 groups, with 2 paired groups of 10 teams and 2 paired of 11 teams. The system was what could be called "complementary round-robin" as teams of one group only played against the teams of the other group paired to it, with no internal round-robin. Top 5 teams of each group qualified for main groups while remaining teams qualified for repechage groups. Group distributions were random. An odd scheduling sometimes reproduced later on for unknown reasons, except urge for randomness.