Per the Wisconsin filing instructions "fill in any amount deducted in computing your federal adjusted gross income that is not allowed as a deduction for Wisconsin or any other addition to income. Enter a description of the addition(s) on the line(s) provided. If you have more than 3 entries, attach a schedule listing each additional entry.
Example
You deducted a passive activity loss on your federal return for losses incurred when you were a resident of another state. The passive activity losses were not allocable to Wisconsin. The passive activity losses are not deductible for Wisconsin and must be included on line 32. Enter "passive activity loss" on the line provided."
For further information, please see the Schedule AD and WI state instructions.