Pricing - exclude a specific category position for discounts

Hi related to the taxable pricing and routine, one request to mantain the aforesaid terms strategy for VBTYP = C,G but I request to exclude for a circumstantial PSTYV the discounts lone for papers G. How tin I do? wherefore successful papers C is moving decently truthful for worldly benignant dien the discount is not moving portion for papers G it is applied?

thanks successful advance