Wis. Stat. § 891.21: Affidavit of notice of corporate meeting.

Whenever any corporation or limited liability company notice is given, posted or served, an affidavit of the person who gave, posted or served the same, specifying the manner and time of doing so, annexed to a copy of such notice, may be filed with the clerk or secretary of the corporation or limited liability company, and when so filed, the original or certified copies thereof, shall be presumptive evidence in all cases of the facts contained in such affidavit.