CLS                      Clear Screen

 CLS

    Clears the screen to the background color and returns the cursor to
    the Home position (row 1, column 1).

   -------------------------------------------------------------------------

      Notes:    CLS clears the entire screen, unless a VIEW statement has
                been used to create a viewport in graphics mode--in which
                case CLS clears only the current viewport.

                CLS resets the "last point referenced" (LPR) so that the
                next graphics command that uses the STEP option references
                the center of the screen.