According to the Parelli system:

Parelli Professionals are talented, dedicated individuals who, after extensive time studying Parelli Natural Horsemanship (PNH) as a student, have been licensed to teach and/or provide horse development training in the field. 
A Parelli Professional is a dedicated and educated horseman, trained to teach students in the Parelli Program. 

Similar to the travel industry, a star rating system is used to rank the Licensed Parelli Professional.  There are a lot of people (inside and outside of PNH) with an opinion of their expertise with horses but without a standard set of criteria by which they and others could measure against.  By looking at a star rating you know what the person has done, how much experience they have and what other related subjects they have studied.  It is important for customers to know what level of education and experience they can reliably expect when they contact a Parelli Professional.

Parelli Professionals are ranked by star rating which reflects their level of tenure and experience teaching the Parelli Program.

Aniek has a 3 star rating ! :-)