def to_s(options={})
      str = encode(options)
      children.each do |child|
        # Note that the extended plan record was introduced in Mosaiq 2.5.
        str += child.to_s(options) unless child.class == ExtendedPlan && options[:version].to_f < 2.5
      end
      str
    end
def to_s(options={})
      str = encode(options)
      children.each do |child|
        # Note that the extended plan record was introduced in Mosaiq 2.5.
        str += child.to_s(options) unless child.class == ExtendedPlan && options[:version].to_f < 2.5
      end
      str
    end
Encodes the record + any hiearchy of child objects,
 to a properly formatted RTPConnect ascii string.

 @param [Hash] options an optional hash parameter
 @option options [Float] :version the Mosaiq compatibility version number (e.g. 2.4) used for the output
 @return [String] an RTP string with a single or multiple lines/records