Michigan Compiled Laws, Chapter 600. Revised Judicature Act of 1961 § 600.1945

Sec. 1945.  The order shall contain the name of the court, the names of the parties, directions as to where and when to answer or take such other action as may be permitted by law, a statement describing the nature of the proceedings, and a statement as to the effect of failure to take the indicated steps.  If the names of some or all of the defendants are unknown, the order shall describe the relationship of the unknown defendants to the matter to be litigated in the best way possible, as for example, unknown claimant, unknown owners, unknown heirs, devisees, legatees, or assigns of a named person.