Format
Throughout its 39-year history, the Cup Winners' Cup was always a straight knock-out tournament with two-legged home and away ties until the single match final staged at a neutral venue, the only exception to this being the two-legged final in the competition's first year. In common with other UEFA club tournaments, the away goal applied when aggregate scores was parity. The format was identical to the original European Champions' Cup with 32 teams contesting four knock-out rounds prior to the showpiece final, with the tournament usually running from September to May each year. In later years, a regular August preliminary round was added to reduce the number of entrants to 32 following the influx of new UEFA member nations during the 1990s.
Entry was restricted to one club from each UEFA member association, the only exception being to allow the current Cup Winners' Cup holders to enter alongside their nation's new domestic cup winners in order to allow them a chance to defend their CWC title (although no club ever managed to do this). However, if this team also qualified for the European Champions' Cup then they would default on their place in the Cup Winners' Cup and no other team would replace them.
On occasions when a club completed a domestic league and cup 'double' that club would enter the European Cup/UEFA Champions League and their place in the Cup Winners' Cup would be taken by the domestic cup runners-up. In 1998/99, the competition's final year, SC Heerenveen of the Netherlands entered the CWC despite only reaching the semi-final of the previous season's Dutch Cup. This was due to both Dutch Cup finalists Ajax and PSV qualifying for the recently expanded Champions League. Heerenveen won a third-place playoff and became the only club to enter the Cup Winners' Cup without having contested their own domestic cup final the previous year.
Read more about this topic: UEFA Cup Winners' Cup