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. Enclose (mail) an explanation of the addition you are including using code 07.
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 4."
For further information, please see the WI state instructions.