39 C.F.R. § 3006.201
(b) Multitrack processing.
(1) Unless expedited processing has been granted, the Commission places each request in simple or complex tracks based on the amount of work and time involved in processing the request. Factors considered in assigning a request into the complex track may include one or more of the following:
(c) Expedited processing.
(1) Requests and appeals shall be processed on an expedited basis whenever it is determined that they involve the following:
(d) Unusual circumstances. Whenever the statutory time limit for processing a request cannot be met because of “unusual circumstances”, as defined in 5 U.S.C. 552(a)(6)(B)(iii), and the Commission extends the time limit on that basis, the Commission shall, before the expiration of the 20 business day period to respond, notify the requester in writing of the unusual circumstances involved and of the date by which processing of the request can be expected to be completed. If an extension will exceed 10 business days, the Commission will: