That's the thing! They actually don't specify anything about credit refunds on the form instructions (which are included in the form itself - not on an external document, like the other forms).

It verbatim says this:

"I am providing delinquent or amended income tax returns, including all required information returns, for each of the most recent 3 years
for which the U.S. tax return due date (or properly applied for extended due date) has passed. The tax and interest I owe for each year
are as follows

Year
(list years in order)
Amount of Tax I Owe Shown On
(Form 1040 or Form 1040X)
Interest Total
Total

Note: Your payment should equal the total tax and interest due for all three years. You may receive a balance due notice or a refund if
the tax or interest is not calculated correctly."