def add_z(bookings)
      data3  = '0256'
      data3 += 'Z'
      sum = 0
      bookings.each do |b|
        sum += b.value.divmod(100)[0]
      end
      data3 += '%015i'   % sum
      data3 += '%015i'   % bookings.count
      data3 += '%0221s'  % ''
      raise "DTAUS: Längenfehler Z (#{data3.size} <> 256)\n" if data3.size != 256
      dta_string << data3
    end
def add_z(bookings)
      data3  = '0256'
      data3 += 'Z'
      sum = 0
      bookings.each do |b|
        sum += b.value.divmod(100)[0]
      end
      data3 += '%015i'   % sum
      data3 += '%015i'   % bookings.count
      data3 += '%0221s'  % ''
      raise "DTAUS: Längenfehler Z (#{data3.size} <> 256)\n" if data3.size != 256
      dta_string << data3
    end
THE MAGICAL Z SEGMENT