Okla. Stat. tit. 51, § 51-96: Summons and pleadings

Upon the filing of the complaint or petition for the writ of

ouster, a summons shall issue for the defendant to appear and answer

the same within twenty (20) days of the service thereof, and there

shall accompany the summons and be served upon the defendant a copy

of the complaint or petition filed against him.

The petition and answer shall constitute the only pleadings

allowed, and all allegations in the answer shall be deemed

controverted, and any and all questions as to the sufficiency of the

petition or complaint shall be raised and determined upon the trial

of the cause; and if said petition is held insufficient in form, the

same shall be amended at once, and such amendment shall not delay

the trial of the case.