WHAT IS THE ITF WORLD TENNIS NUMBER (WTN)?
The WTN is a global rating scale that allows tennis players to find the right playing partner or program. It is a scale between 40 and 1, with 40 being a beginner player and 1 being an elite professional. This scale is for all players, regardless of age, gender, or ability. Players will have a separate WTN for both singles and doubles.
https://www.tenniscanada.com/tournaments/world-tennis-number/