The Purchasing Agent or any Provo City department or division may prepare, file, or amend specifications, requisitions, or quantity estimates for supplies and services in the manner prescribed by the Purchasing Policy Manual. Under the direction of the Mayor, a purchasing official shall have authority to revise specifications, requisitions or estimates as to quantity, quality or estimated cost. All specifications shall seek to promote overall economy and best use for the purposes intended and encourage appropriate competition in satisfying the City’s needs.