Wis. Stat. § 6.869
The commission shall prescribe uniform instructions for municipalities to provide to absentee electors. The instructions shall include the specific means of electronic communication that an absentee elector may use to file an application for an absentee ballot and, if the absentee elector is required to register, to request a registration form or change his or her registration. The instructions shall include information concerning whether proof of identification is required to be presented or enclosed. The instructions shall also include information concerning the procedure for correcting errors in marking a ballot and obtaining a replacement for a spoiled ballot. The procedure shall, to the extent possible, respect the privacy of each elector and preserve the confidentiality of each elector's vote.
Wis. Stat. § 6.869