I have the same question. My financial institution did not provide any information for any sub-part to block 6, including block 6d, yet there is an amount in block 6. The IRS does not mention anything about sub-parts to block 6 in the Form 1099-DIV either (<a rel="nofollow" target="_blank" href="
https://www.irs.gov/forms-pubs/about-form-1099-div-dividends-and-distributions">https://www.irs.gov/...>).
