This is a user-defined operand that retrieves the CLA (Data 0) and CTR (Data 1) columns of the Seidel Coefficients based on the wave number (Hx) and surface number (Hy).
This is related to this OpticStudio community post: https://community.zemax.com/got-a-question-7/color-correction-of-a-lens-group-5021