invoice st tolerance limit

Hello

In tolerance limits there is an limit type called ST.

İt works like this:

• ST: Date variance (value x days)
• The system calculates for each item the product of amount * (scheduled delivery date - date invoice entered) and compares this product with the absolute upper limit defined. This allows relatively high schedule variances for invoice items for small amounts, but only small schedule variances for invoice items for large amounts.

My question is;

What is the meaning of product of amount?