Maximum discount by line item during SO Entry

SOLVED

My client has hundreds of product lines with corresponding vendors that allow maximum discount percentages on their products. For example product line AAA has a maximum discount of 30%, where product line ABA allows a maximum discount of 35%.

With so many product lines, salesmen need reminders (?) or restrictions during SO Entry on how much discounts they can apply to line items based on maximum discount allowed by vendor. What would be the best way to achieve this objective?

Thank you in advance,

KVO