SET(DISPLAY_VALUE)
     Sets the display value of the specified window.  DECTPU uses a window's
     display value, which is an integer value, to determine if a given
     record in a buffer should be made visible in a given window.  If the
     record's display value is greater than or equal to the window's
     setting, DECTPU makes the record visible in that window; otherwise,
     DECTPU makes the record invisible.  To set a record's display value,
     use the SET (RECORD_ATTRIBUTE) built-in.
  Syntax
     SET (DISPLAY_VALUE, window, display_value_integer)
  Parameters
      DISPLAY_VALUE          A keyword indicating that the SET built-in is
                             being used to set the display value for a
                             window.
      window                 The window whose display value you want to set.
      display_value_integer  An integer from -127 to +127.
  Example
     The following statement gives the current window a display value of 10.
     This means that any record whose display value is less than 10 is
     invisible in the specified window.
     SET (DISPLAY_VALUE, CURRENT_WINDOW, 10);
  Related Topics
     GET_INFO(BUFFER_VARIABLE)          GET_INFO(MARKER_VARIABLE)
     GET_INFO(WINDOW_VARIABLE)          SET(ERASE_UNMODIFIABLE)
     SET(LEFT_MARGIN)                   SET(MODIFIABLE)
     SET(RECORD_ATTRIBUTE)