Zu den Regeln:
ITTF Handbook
ITTF Handbook Chapter 3
3.08 INTERNATIONAL ELIGIBILITY
3.08.01 Eligibility in Olympic title competitions is regulated separately by 4.5.1 and eligibility in Paralympic title competitions is regulated separately by the IPC and 4.6.1; additional eligibility regulations apply to World title events (4.1.3, 4.2.3, 4.3.6, 4.4.3)
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3.08.03 A player is eligible to represent an Association only if he or she is a national of the country in which that Association has jurisdiction, except that a player who has already represented an Association of which he or she was not a national in accordance with previous rules may retain that eligibility.
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3.08.05 A player shall not represent different Associations within a period of 3 years.
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ITTF Handbook Chapter 4
4.01.03 Eligibility
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4.01.03.02 In addition to provisions of 3.8, players who have acquired a new nationality and wish to represent the association corresponding to the new nationality shall register with ITTF through this new Association.
4.01.03.03 Such player shall not represent the new association before
4.01.03.03.01 3 years after the date of registration, if the player is under the age of 15 when registered;
4.01.03.03.02 5 years after the date of registration, if the player is under the age of 18 but at least 15 years of age when registered;
4.01.03.03.03 7 years after the date of registration, if the player is under the age of 21 but at least 18 years of age when registered.
4.01.03.04 Players being 21 years of age or older will not be registered with the ITTF and will not be eligible to represent a new association at World Championships.