Within 30 days after service of the writ of certiorari, or within any further time as the court allows, the agency shall transmit to the reviewing court the original or a certified copy of the entire record of the proceeding under review. By stipulation of all parties to the review proceeding, the record may be shortened. Any party unreasonably refusing to stipulate to limit the record may be taxed by the court for the additional costs. The court may require or permit subsequent corrections or additions to the record when deemed desirable.