(a) Any party to a proceeding before the Commission may appeal from any final order or decision of the Commission within 30 days after the entry of the final order or decision, or within an additional time fixed by the Commission, not to exceed 30 additional days, and by order made within 30 days, if the party aggrieved by the decision or order files with the Commission a notice of appeal that sets forth specifically the ground or grounds on which the aggrieved party considers the decision or order to be unlawful, unjust, unreasonable, or unwarranted and that includes the errors alleged to have been committed by the Commission. All other parties may give a notice of cross-appeal that sets forth specifically the grounds on which the party considers the decision or order to be unlawful, unjust, unreasonable, or unwarranted and that includes the errors alleged to have been committed by the Commission. The notice of cross-appeal shall be filed with the Commission within 20 days after the first notice of appeal has been filed, or within an additional time fixed by the Commission, not to exceed 20 additional days by order made within 20 days of the first filed notice of appeal.