VMS Help TCPIP Services, TELNET, TN3270 Keyboard Functions, CLEAR  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    VT100: EXT + Enter          VT200: EXT + F20
    DEFINE_KEY Function: CLEAR

    Clears the screen and moves the cursor to the first position
    on the screen. When you invoke the CLEAR function, the software
    notifies the application program that this function has been
    used.