An IBM-supplied or user-supplied application program that uses full-screen I/O in TSO full-screen mode can be used to manage the screen. TSO/VTAM uses the screen size used by the application program. If the CLEAR key is pressed, TSO/VTAM erases the screen with either an Erase/Write (EW) or Erase/Write Alternate (EWA) command depending on which was last used by the application program.