Allows the reversal or void of the full or partial amount charged against one or more fund categories on a payment. Fund category reversals support partial reversals by specifying an amount as part of the request body. When the amount field is omitted, the full remaining balance of items in that category is reversed. When provided, only the specified amount is reversed, allowing for partial category reversals. Paycore will select which items to reverse within each category using a knapsack algorithm, preferring full-item reversals over partial ones.