# File lib/edi4r.rb, line 811
    def to_s
      str = self.value
      return str if str.is_a? String
      str = str.to_s; len = str.length
      return str unless format =~ /n(\d+)/ && len != (fixlen=$1.to_i)
      raise "#{location}: Too long (#{l}) for fmt #{format}" if len > fixlen
      '0' * (fixlen - len) + str
    end