The title of each sheet of such final map shall consist of the approved name and unit number of the tract; if any; at the lower right hand corner of the sheet; followed by the words "City of Petaluma." Maps filed for the purpose of showing as acreage land previously subdivided shall be conspicuously marked with the words "Reversion to Acreage." (Ord. 1046 NCS §1 (part), 1972; prior code §22.6.302.)