Oregon Revised Statutes Insurance § 732.320

(1) A voucher signed by or on behalf of the person receiving the money or, if a voucher cannot be obtained, by an affidavit stating the reason for not obtaining the voucher;

(2) A bill, invoice, statement or similar document commonly in business use submitted on account of goods supplied or services rendered or both;

(3) An authorization of the board of directors, or a committee thereof or officer duly delegated by the board with authority to so authorize, in regard to compensation of officers, employees and agents; or

(4) Satisfactory proof of claim, accepted and approved in the manner prescribed by the insurer, based upon provisions of a policy issued by the insurer.