Section 510.4 - Multitrack processing(a) When ARS has a significant number of requests, the nature of which precludes a determination within 20 working days, the requests may be processed in a multitrack processing system, based on the date of receipt, the amount of work and time involved in processing the request, and whether the request qualifies for expedited processing.(b) ARS may establish as many processing tracks as appropriate; processing within each track shall be based on a first-in, first-out concept, and rank-ordered by the date of receipt of the request.(c) A requester whose request does not qualify for the fastest track may be given an opportunity to limit the scope of the request in order to qualify for the fastest track. This multitrack processing system does not lessen agency responsibility to exercise due diligence in processing requests in the most expeditious manner possible.(d) ARS shall process requests in each track on a "first-in, first-out" basis, unless there are unusual circumstances as set forth in § 1.16 of this title, or the requester is entitled to expedited processing as set forth in § 1.9 of this title.