If none of the other detail checkboxes apply you would have to mark the box for I Have Another Description Item and enter the amount somewhere else in TurboTax (in addition to entering it on TurboTax's K-1 form) according to the instructions provided by the partnership or the IRS instructions for partners receiving a Schedule K-1 (Form 1065). There is more than a page and a half of partner instructions for code I: https://www.irs.gov/pub/irs-pdf/i1065sk1.pdf
