They're referring to the packet that the company sends out in advance of the interview. (application, interview directions, additional info/instructions, etc).
Personally when I interview, I take a leather bound 3 ring portfolio (like a legal pad sized planner). In it I have 5 copies of my: latest resume, color copies of my certificates and medical, the last page of my logbook (printed out), and my current (past 30 days) driving record.
Those I offer as "updates" to the on file info when I interview.