The first Six Nations tournament was held in 1971 in Belgium. Six teams to take part in the premier edition were Holland, Belgium, France, Germany, Switzerland and England. This has slightly changed recently: Ireland, Sweden and Austria have occasionally taken part. The tournament has been organized as much as 21 times already and is held every two years (odd). The teams play five rounds in three days, each team eligible to field four players and no reserves. Until 1985 only three rounds were played but since the tournament was organized for the first time in the Netherlands the number of rounds was extended to five. / Info taken from
Dutch Blind Chess Association site /