Mich. Comp. Laws § 211.10e
All assessing officials whose duty it is to assess real or personal property on which real or personal property taxes are levied by any taxing unit of the state shall use only the official assessor's manual or a manual approved by the state tax commission consistent with the official assessor's manual, with their latest supplements, as prepared or approved by the state tax commission as a guide in preparing assessments. Beginning with the tax assessing year 1978, all assessing officials shall maintain records relevant to the assessments, including appraisal record cards, personal property records, historical assessment data, tax maps, and, through calendar year 2018, land value maps, consistent with standards set forth in the assessor's manual published by the state tax commission.
MCL 211.10e