(a) Every order, finding, authorization, rule, or certificate issued or approved by the commission under any provisions of this act shall be in writing and entered on the records of the commission, all of which shall be public records.
(b) A certificate under the seal of the commission that any such order, finding, authorization, rule, or certificate has not been modified, stayed, suspended, or revoked shall be received as evidence in all courts as to the facts therein stated.