Class IV: Four other citizens of the municipality, to be appointed by the Mayor. The members of Class IV shall hold no other municipal office, position or employment. If there be a Municipal Environmental Commission, the member of the Environmental Commission who is also a member of the Planning Board, as required by Section 1 of P.L. 1968, c. 245 (C. 40:56A-01), shall be a Class IV Planning Board member, unless there be among the Class IV or alternate members of the Planning Board both a member of the Zoning Board of Adjustment or Historic Preservation Commission and a member of the Board of Education, in which case the member common to the Planning Board and Municipal Environmental Commission shall be deemed a Class II member of the Planning Board. For the purpose of this section, membership on a municipal board or commission whose function is advisory in nature, and the establishment of which is discretionary and not required by Statute, shall not be considered the holding of municipal office. Two Class IV members shall be appointed as alternates. See § 25-212.