37 CFR 1.985: Notification of prior or concurrent proceedings in inter partes reexamination.

(a) In any inter partes reexamination proceeding, the patent owner shall call the attention of the Office to any prior or concurrent proceedings in which the patent is or was involved, including but not limited to interference or trial before the Patent Trial and Appeal Board, reissue, reexamination, or litigation and the results of such proceedings.

(b) Notwithstanding any provision of the rules, any person at any time may file a paper in an inter partes reexamination proceeding notifying the Office of a prior or concurrent proceeding in which the same patent is or was involved, including but not limited to interference or trial before the Patent Trial and Appeal Board, reissue, reexamination, or litigation and the results of such proceedings. Such paper must be limited to merely providing notice of the other proceeding without discussion of issues of the current inter partes reexamination proceeding.