= b command
        .set destination to the previous line of "b" command line,
         then execute "a" command.
         See "a" command for effect of n,b,s.
        .Specify "B"(Binary copy option) just after "B"(before) cmd.
           bbn,b.s
        .Specify "C"(CID copy option) after "B" if exist.
           b[b]cn,b.s

        .copy just before the line.

            c3     |A
            0000002|B
            0000003|C
            0000004|D
            0000005|E
            b      |F
            0000007|G
        ===>
            0001000|A
            0002000|B
            0003000|C
            0004000|D
            0005000|E
            0005100*A
            0005200*B
            0005300*C
            0006000|F
            0007000|G