Accepted by the International Union of Speleology (UIS) at the General Assembly at the 12th International Congress of Speleology (La Chaux-de-Fonds, Switzerland, 1997)

Modified by the General Assembly at the 13th International Congress of Speleology (Brasilia, Brazil, 2001), and the 16th International Congress of Speleology (Brno, Czech Republic, 2013)