Repeats execution of the last command SDA executed.  This command can also
    be invoked by pressing the 0 key on your terminal's keypad (KP0).

    This command provides a convenient method of displaying a series of data
    structures in a linked list or examining a sequence of locations.  For
    example:

        FORMAT @IOC$GL_DEVLIST  ! Start at first DDB in system
        FORMAT @.               ! Skip to next entry in list
        <KP0>                   ! Repeat FORMAT @. command
        .
        .
        .