Foreign tax Statement of Explanation

I have 967$ in foreign tax credit that is from mutual fund dividends. During the questionnaire on foreign tax credit I marked RIC and used my 1099 Div statement from my Vanguard Brokerage to calculate the dollar amount from foreign investments.

I have done this in previous years with no problem but this year I am being asked to fill out an explanation statement for form 1116, "It must show the other deduction items for Line 3B, Col. A.

I have no idea what this is and why I need to fill this out.

Any help would be appreciated.

Thanks