FA Premier League
All professional football leagues have a regulation concerning the kit of the teams. Most of the times they contain some articles about the shirt numbers, especially about the colours and measures. The UEFA also has quite strict rules concerning the application of numbers on striped shirts.
The English Football Association prescribes a special shirt number design for all teams that participate in the Premier League.
The Olympic Tournament is another example of a sports competition in which the design of the shirt numbers is prescribed by the organisation.