2 substitutes were allowed in the cups 1986/87, in the league from 1987/88 and in European competitions in the 1967/68 season (rising to 3 in Europe the following season). A goalkeeper became a firm fixture on the bench in the league in 1992/93, a year later the cups followed suit. Before 1992, if a goalkeeper got injured, a replacement keeper was permitted.
Since 1994/95 five subs have been allowed in league games. 5 were allowed in European games since the 1969/70 season, the number rising to 7 in the 1997/98 season. The cup competitions only allowed 3 in 1994/95, but raised the number to 5 in 1998/1999.
Information about players, who made the bench, but did not make an appearance is available from 1975/76.
The exact time a substitution was made is available in this database from the 1987/88 season onwards.