The administration of this chapter is vested in the following five offices of the government of the city: Building Official, Zoning Enforcement Officer, Planning and Zoning Commission, Board of Adjustment and the City Council. The following sections shall first set out the authority of each of these four offices, and then describe the procedure and substantive standards with respect to the following administrative functions: issuance of zoning certificates and occupancy permits, variances, appeals, uses on review and other powers of the Commission and Board and amendments.