vendor evaluation - single / sole source

Hi experts:

     i am confused about the indicator "single / sloe source". the path is spro->purchasing ->vendor evaluation - >maintain purchasing organization data.

it is said  " the system does not calculate a score for the price level and price history,  if you do not set the indicator " .  when i do not set this indicator and do test in the frontend. the score of "Price Level"in log is 0, but it is considered as 100 points.

     ps: i do not set the market price for this material and the vendor is the single source.

Best Regards

Charles