Unlike in ex parte reexamination, a third party requester may participate at every stage of the proceedings. A third party requester (TPR) may once file written comments on any response by the patent owner to an Office action. 35 USC 314(b)(3). All proposed grounds of rejection raised by the TPR, and all TPR comments must be specifically addressed by the examiner. The TPR may appeal any proposed ground of rejection not adopted by the examiner as a final decision favorable to patentability to the Board of Patent Appeals and Interferences (BPAI) under 35 USC 134, and to the Federal Circuit under 35 USC §§ 141-144. 35 USC 315(b)(1). The TPR may be a party to nay patent owner appeal of a rejection to the BPAI under 35 USC 134, and to the Federal Circuit under 35 USC §§ 141-144. 35 USC 315(b)(2). A TPR cannot file an inter partes reexamination request: (1) while a first inter partes reexamination is ongoing -35 USC 317(a); (2) where a final decision has been entered against the TPR in a civil action, the TPR cannot request or maintain an inter partes reexamination based on the same issues-35 USC 317(b); (3) where a final decision has been entered against the TPR in an inter partes reexamination that is favorable to the patent owner, the TPR cannot request or maintain an inter partes reexamination based on the same issues-35 USC 317(b); and (4) for a any patent that issued from an original application filed in the U.S. before November 29, 1999-Section 4608 of P.L. 106-113. Estoppel attaches against any TPR in a later civil action if the TPR loses: as to reasserting grounds of invalidity against challenged patent claims-35 USC 315(c) or as to challenging facts established in the reexamination proceedings-Section 4607 of P.L. 106-113. USPTO reexamination rules were clarified in 2006 to require that in order for a filing date to be accorded to an inter partes reexamination request the request must meet all applicable statutory requirements of 35 USC 311. Final rule-71 Fed. Reg. 44219, August 4, 2006. This provides the Office, the patent owner and the public with a better understanding of the nature of and a focusing of the requester’s challenge. To receive a filing date there must be a statement identifying each substantial new question of patentability (SNQ) and proposed ground of rejection. Every patent claim for which reexamination is requested must be identified. How all cited documents apply to the claims and are applied in a corresponding SNQ/proposed rejection must be explained in detail. For each identified SNQ/proposed rejection, the request must explain how all the cited documents identified for that SNQ/proposed rejection are applied to meet/teach the claim limitations, to thus establish the identified SNQ/proposed rejection. This practice change prohibits general SNQ statements such as-the claims are obvious over any of references A, B, C, and D, taken alone or in combination. It also prohibits citation of references in the request without statements of how the references are applied to the claims. If the reexamination request is for fewer than all the patent claims, the USPTO will generally review only the claims for which reexamination is requested that raise an SNQ. The USPTO may, however, exercise its discretion to examine nonrequested claims – where the expenditure of added resources is deemed justified. 1311 Off. Gaz. Pat. Office 197 (October 31, 2006).