In Europe there is a well-defined third tier of tours which are independently operated but offer promotion to the Challenge Tour for the most successful players. The four third level tours, known as the Satellite Tours, are the PGA EuroPro Tour, the Alps Tour, the Pro Golf Tour and the Nordic Golf League. Starting July 2015, the four Europe-based third-tier tours will factor into the OWGR rankings. Below this level there are various minor professional tournaments, some of which are organised into series by national golf associations.