Iowa Code § 29A.24
There shall be maintained in the office of the adjutant general a list to be known as the unassigned list, to which officers may be transferred, pending their resignation or removal from the service. Any officer may be transferred by the adjutant general to such unassigned list upon the recommendation of the officer's commanding officer, either immediate or remote. Before such transfer is made the adjutant general shall notify the officer, either in person or by certified mail mailed to the officer's last known address of the intended transfer. The officer shall have ten days from the date of mailing of said notice in which to apply to the adjutant general for an efficiency board. Should the officer fail to apply for an efficiency board, the transfer shall be made upon the expiration of the ten-day period. If the officer requests an efficiency board, the adjutant general will be governed by the finding of such board. All officers transferred to such unassigned list shall remain subject to military discipline and to courts-martial for military offenses to the same extent and in like manner as if upon the active list.
Iowa Code § 29A.24