@type t() :: %HL7v2.Segment.RF1{
  effective_date: term(),
  expiration_date: term(),
  external_referral_identifier: term(),
  extra_fields: term(),
  originating_referral_identifier: term(),
  process_date: term(),
  referral_category: term(),
  referral_disposition: term(),
  referral_priority: term(),
  referral_reason: term(),
  referral_status: term(),
  referral_type: term()
}