Terminal Productivity Executive (TPX), is a multiple session manager on IBM Mainframes i.e. in z/OS. It allows connected users to access resources with a single sign-on: It holds several sessions concurrently, allowing a person to switch among them via the single connection on their physical terminal or terminal emulator application, i.e. telnet. For each session, TPX uses a virtual terminal. I.e. users can use it to switch amongst ISPF and SDSF in the TSO.