Official FIDE announcement:
FIDE has noticed that a private company from Germany, named "Amateur Chess Organisation (ACO)" is advertising events with the misleading name “World Senior Chess Championships” supposed to be held in Crete, Greece in October 2018. These events do not have any official recognition from FIDE. Furthermore, the above mentioned private company is abusing the FIDE ratings and the title "World Championships" to misguide players into believing that these events might be official world championships.
FIDE is the only global organisation recognised by the International Olympic Committee (IOC) to hold the World Championships in chess of all categories and age groups. FIDE also informs its national federations and their players that these so called by ACO "World Senior Chess Championships" are not the official FIDE championships and they will not be included in the FIDE rating list.
The only official and real World Senior Chess Championships 2018 are organized this year by FIDE in Slovenia, from 17 to 30 November, and the official website is wscc2018.european-chessacademy.com
FIDE is obliged to protect all member National Chess Federations and their players from practices of misleading and fake “World Championships”. The relevant FIDE administrative bodies will soon examine the issue in detail and in accordance with the FIDE regulations for the registration and licensing of organisers, players, trainers and arbiter.