It is not unusual for a trademark to be assigned while a TTAB inter partes proceeding is pending. In that case, a party typically moves to join or substitute a party under Fed. R. Civ. P. 19, 20, and TBMP Sec. 512. If an assignment occurred before the proceeding began, or if the assignor no longer exists, or if plaintiff does not object, or if the testimony periods have closed, then the assignee may be substituted as a party. In all other cases, the assignee may be joined as a party. If a party is inadvertently misidentified in the initial petition or opposition, then, depending on the facts, the TTAB may allow a moving party to correct the mistake and substitute the proper party of interest.