On Tru64 UNIX you can define symbols to represent commonly used
    class/instance pairs of NCL commands.  Use the undefine control verb
    to delete symbols.

    undefine symbol-name

    For more information, referto HELP NCL CUSTOMIZING DEFINING_SYMBOLS.

    Examples:

    ncl> undefine Ether,Remote_Node  ! To delete specific symbols

    ncl> undefine *                  ! To delete all remaining symbols