Okla. Admin. Code § 330:1-5-7
The formal rules of pleading and evidence need not be observed; however, effect shall be given to the rules of privilege recognized by the laws of the State of Oklahoma. Documentary evidence may be received in the form of copies or excerpts if the original is not readily available, and upon request a party shall be given an opportunity to compare the copy with the original. Notice may be taken of judicially cognizable facts and of generally recognized technical or scientific facts within the specialized knowledge of the Trustees. The Trustees' experience, technical competence and specialized knowledge shall be utilized in the evaluation of evidence. Objections to evidentiary offers shall be allowed and noted on the record.
Okla. Admin. Code § 330:1-5-7