Bill Bulat
Ansys Employee
DX uses the ranges of objectives to evaluate the rating of the candidate points.
For example, if you want to minimize P1, and the value for P1 for your candidate point is close to the maximum value obtained for all your Dessign Points generated during your  optimization (and DOE + Response Surface refinement, if your optimization is based on RS), then your rating will be equal to 3 stars, if P1 is close the maximum known value of P1, the rating will be equal to 3 cross, and when P1 is close to the middle of the range, then the rating will be the neutral symbol...
 
More details here in the doc (see example at the end):