# File lib/spreadsheet/workbook.rb, line 131
   def store_all_fonts
      font = @format.font_biff
      for n in 1..5
         append(font)
      end

      fonts = Hash.new(0)
      index = 6
      key = @format.font_key
      fonts[key] = 0

      @formats.each{ |format|
         key = format.font_key
         if fonts.has_key?(key)
            format.font_index = fonts[key]
         else
            fonts[key] = index
            format.font_index = index
            index += 1
            append(format.font_biff)
         end
      }
   end