Okla. Stat. tit. 12 § 421 : Civil Procedure — Evidence —General Provisions — Three Modes of Taking Witness Testimony TEXT PDF The testimony of witnesses is taken in three modes: First. By affidavits. Second. By deposition. Third. By oral examination. Okla. Stat. tit. 12, § 421 R.L. 1910, § 5067.