Some names in the list are already resolved. For example while 'GER' is not a standard country code but with its more than twenty thousand players it can not be any other country than Germany. But some of the resolved names may be wrong. For example I'm not sure that 'MAS' stands for Malaysia.
If you can spot incorrectly resolved country codes please let me know.
For the thread concerned with the popularity of chess worldwide I compiled a list of the number of registered players per country based on the nationality data extracted from the XML format players list downloadable from Fide.
The problem is that Fide country codes are not all according to the ISO standard.
If anyone can identify the countries with question marks in this list please do it: