A municipality that opts to prepare its budget pursuant to the Municipal Budget Act may select a budget format based on funds and departments or, in the alternative, it may select a format based on purpose. A purpose-based budget shall be subject to all other requirements of the Municipal Budget Act, except those requirements specifically related to budgeting by fund or as provided in Sections 4 and 5 of this act.
Okla. Stat. tit. 11, § 17-203.1