noun: Initialism of parent-teacher association. [A formal organization composed of parents, teachers, and staff that is intended to facilitate parental participation in a public or private school.]
noun: Initialism of prepaid ticket advice: information sent to an airline that a passenger will collect the ticket at the airport (not the same as an e-ticket).
noun: (Australia, firearms) Initialism of permit to acquire: a form lodged with the police to aquire a specific firearm; the authorisation subsequently acquired.