Source : Free On-Line Dictionary of Computing

Terminal Productivity eXecutive
     
         (TPX) A multiple session manager used to
        access {mainframe} applications.  TPX allows you to work in
        multiple mainframe applications concurrently; lock and unlock
        your TPX screen; place your applications on hold; logon on to
        TPX from a different terminal without losing your place;
        customize your TPX menu; and send a screen image to another
        TPX user.
     
        [What does it run on?]
     
        (2000-05-08)