= Page scroll

        {UP | DOWn | LEFt |RIGht} [p | page | h | half | c | csr
                                  | m | max | (nn)]}
            p/page  :by a Height or Width.
            h/half  :by a half of Height or Width.
            c/csr   :Move the point of cursor to the edge of screen.
            m/max   :diaplsy file top-line/end-line/left-column/right-
                     last-column-of-displayed-line.
            nn      :number of Lines or Columns to scroll.

            -It may work to input operand only then press each function
             key,but alternatively you can fix scroll value by entering
             it on scroll field of command line(===>HALF ).