VMS Help TN3270, Qualifiers, /KEY_DEFINITIONS  *Conan The Librarian (sorry for the slow response - running on an old VAX)

       /KEY_DEFINITIONS=file

    Optional. Default: default keyboard layout.

    Keyboard definition file you created to redefine how the TN3270
    key functions correspond to your keyboard layout. This file holds
    the definitions for alternative keyboard mapping.