# File lib/spreadsheet/olewriter.rb, line 96
   def write_header
      return if @biff_only == true
      calculate_sizes
      root_start = @root_start

      write([0xD0CF11E0, 0xA1B11AE1].pack("NN"))
      write([0x00, 0x00, 0x00, 0x00].pack("VVVV"))
      write([0x3E, 0x03, -2, 0x09].pack("vvvv"))
      write([0x06, 0x00, 0x00].pack("VVV"))
      write([@list_blocks, root_start].pack("VV"))
      write([0x00, 0x1000,-2].pack("VVV"))
      write([0x00, -2 ,0x00].pack("VVV"))

      unused = [-1].pack("V")

      1.upto(@list_blocks){
         root_start += 1
         write([root_start].pack("V"))
      }

      @list_blocks.upto(108){
         write(unused)
      }
   end