= n command
         .only overwrite method is different with "p" command.
          p cmd:paste all chars of the source line.
          o cmd:only space chars of destination line are overwritten
                by char of corresponding position of source line.
          n cmd:only non-space char of source line are selected
                and overwrite correspondiong postion of destination line.

            c      |  :  :  .
            nn     |01.23.51-123
            0003000|01.23.55-228
            0004000|01.24.12-560
            0005000|02.13.01-125
            0006000|02.43.33-063
            nn     |03.03.34-970
        ===>
            0001000|  :  :  .
            0002000*01:23:51.123
            0003000*01:23:55.228
            0004000*01:24:12.560
            0005000*02:13:01.125
            0006000*02:43:33.063