CST - maximum delta in adaptive mesh refinement

CST 2020

CST Studio Suite  I am a bit confused about the definition of delta s in adaptive mesh refinement systems. According to the "help" page,the definition of delta S is" The change in the S-parameters is determined as the maximal deviation of the absolute value of the complex difference of the S-parameters between two subsequent passes". But I calculate the maximum value of the absolute value of the complex difference of the S-parameters between two subsequent passes,using the real and imaginary data of S-parameters, and find out it can't match with the value given by CST. So I really wonder the definition of ''maximum delta'' and the meaning of ‘maximal deviation‘.