26 have not been reissued by Chelsea since they left the club in 20 respectively. Although it has not been officially retired, Gianfranco Zola's No. In Britain, only Bobby Moore's, Jack Lester's and Jude Bellingham's shirt numbers have been retired due to great service to the club as opposed to a tragic incident. Also, Norwegian club Fredrikstad retired Dagfinn Enerly's number following an on-pitch accident that left him paralysed. In some cases, such as those of Jason Mayélé, Vittorio Mero, Marc-Vivien Foé, Miklós Fehér, Ray Jones, Dylan Tombides, François Sterchele, David di Tommaso, Antonio Puerta, Besian Idrizaj, Piermario Morosini and Davide Astori, numbers have been retired to posthumously honour a player who died while still active. It honours a player who has meant so much to his club that they retire the shirt number that the player wore during their time there, meaning no other player is permitted to use that number in the future. Retiring a player's number usually occurs after the player has left the team or retired. Mexico was pioneer country in the use of permanent numbers in football, being adopted in Primera División in the 1980s. Moreover, Pelé's #10 was retired by the New York Cosmos during the farewell of the Brazilian star on 1 October 1977, probably becoming the first number ever retired in association football.
Nevertheless, in the American league NASL, players always wore permanent numbers since its inception in 1967.
Before then, it was typical for players in the starting lineup to be issued numbers 1 to 11 by formation/position on a match-by-match basis, and substitutes to be numbered from 12 upwards, meaning a player might wear different numbers during the season if they were to play in different positions for tactical reasons, or simply not be a regular in the starting lineup. This practice, long established in the major North American sports, is a recent development in football since squad numbers for specific players were not widely used until the 1990s. The number 10 he wore was retired by Napoli in 2000. Signed jersey worn by Diego Maradona during his tenure on Italian club Napoli, exhibited at the San Siro Museum of Milan.