What IOC strict rule you were referring to? Pls share?
I don't have time to find it
you can google it
I think this was in place for over 12 years already,
after 2004 i think or before
ITTF Handbook (2016)
4: Regulations for World, Olympic and Paralympic Title Competitions
4.1 World Championships
4.1.3 Eligibility
4.1.3.1
Only an Association which is not in arrears (1.16.3.3) and has taken part with at least one player or team (an entry) in its preceding Continental Championships, including qualification tournaments, or Continental Games, shall be eligible to enter teams or individual players in the Championships.
4.1.3.2
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.
4.1.3.3
Such player shall not represent the new Association before:
4.1.3.3.1
3 years after the date of registration, if the player is under the age of 15 when registered, but only 1 year after the date of registration if the player has never represented another association;
4.1.3.3.2
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;
4.1.3.3.3
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.
4.1.3.4
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.
4.5 OLYMPIC COMPETITIONS
4.5.1 Eligibility
4.5.1.1
To be eligible for participation in the Olympic Games a player, coach or official shall comply with the Olympic Charter as well as with the ITTF rules. In particular the above mentioned persons shall
4.5.1.1.1
be entered by their National Olympic Committee (NOC);
4.5.1.3
Any player shall be a national of the country of the NOC which is entering him or her.
4.5.1.3.1
A player who is a national of 2 or more countries at the same time may represent either one of them, as he or she may elect.
4.5.1.3.2
After having represented one country in the Olympic Games, in continental or regional games or in world or regional championships recognised by the ITTF, a player may not represent another country unless he or she meets the conditions set forth in 4.5.1.3.3.
4.5.1.3.3
A player who has represented one country in the Olympic Games, in continental or regional games or in world or regional championships recognised by the ITTF and who has changed his or her nationality or acquired a new nationality, may participate in the Olympic Games to represent his or her new country provided that at least 3 years have passed since the player last represented his or her former country.
4.5.1.3.4
The 3-years-period mentioned in 4.5.1.3.3 may be reduced or even cancelled, with the agreement of the NOCs concerned and the ITTF Executive Committee, by the IOC Executive Board, which takes into account the circumstances of each case.
4.5.1.3.5
If an associated state, province or overseas department, a country or colony acquires independence, if a country becomes incorporated within another country by reason of a change of border, or if a new NOC is recognised by the IOC, a player may continue to represent the country to which he or she belongs or belonged. However, he or she may, if he or she prefers, choose to represent his or her country or be entered in the Olympic Games by his or her new NOC if one exists. This particular choice may be made only once.
4.5.1.4
All disputes relating to the determination of the country which a player may represent in the Olympic Games and in particular issue specific requirements relating to nationality, citizenship, domicile or residence of the player, including the duration of any waiting period, shall be resolved by the IOC Executive Board
http://www.old.ittf.com/ittf_handbook/2016/2016_ITTF_HB.pdf
Regulations for World Cup are the same as for World Championships.
Cheers,
BLUE