Query Parameter Definition (QPD) segment -- HL7v2 v2.5.1.
Contains query parameter definitions. Fields beyond 2 are query-specific and carried as :raw. 3 fields per HL7 v2.5.1 specification (minimum).
@type t() :: %HL7v2.Segment.QPD{ extra_fields: term(), message_query_name: term(), query_tag: term(), user_parameters_in_successive_fields: term() }