708 — A petition for review in a court of appeals is generally very bare bones. It is not a brief; it does not make an argument. Its function is to give notice. For example, the D.C. Circuit provides this template of a petition for review. Or have a look at the petition for review in West Virginia v. EPA, which ended up in the Supreme Court (where it produced the Major Questions Doctrine). On the other hand, some lawyers take the opportunity to go into some detail about the agency’s claimed errors and abuses, as with a complaint in district court, hoping to get a head start in controlling the narrative.