The basic pay ranges established under Secs. 9701.321 through 9701.323 may be supplemented in appropriate circumstances by locality or special rate supplements, as described in Secs. 9701.332 through 9701.335. These supplements are expressed as a percentage of basic pay and are set and adjusted as described in Sec. 9701.334. As authorized by Sec. 9701.356, DHS implementing directives will determine the extent to which Secs. 9701.331 through 9701.337 apply to employees receiving a retained rate.