37 CFR § 2.112 - Contents of petition for cancellation.
(a) The petition for cancellation must set forth a short and plain statement showing why the petitioner believes he, she or it is or will be damaged by the registration, state the ground for cancellation, and indicate, to the best of petitioner's knowledge, the name and address, and a current email address(es), of the current owner of the registration. ESTTA requires the petitioner to select relevant grounds for petition to cancel. The required accompanying statement supports and explains the grounds.
(b) When appropriate, petitions for cancellation of different registrations owned by the same party may be joined in a consolidated petition for cancellation. The required fee must be included for each party joined as a petitioner for each class sought to be cancelled in each registration against which the petition for cancellation has been filed.