HL7 QPD Query Parameter Definition

Query and response fields from experience.
HL7 field reference QPD fields from HL7 v2.5.1 Show fields

These are the generated fields for the version selected at the top of the page. The document stays the same, but the reference panel follows that version.

Fields

FieldNameRequiredRepeatableTypeTable
QPD.1 Message Query Name Yes No CE 0471
QPD.2 Query Tag No No ST
QPD.3 User Parameters (in successive fields) No No var

QPD defines a query by profile and parameters in modern QBP-style query messages.

Query segments define what the sender is asking for, how the receiver should format the answer, and how a multi-message response is continued or limited.

A query is an interface contract. The tag, parameters, row definitions, sort/filter rules, and continuation pointers must match exactly or the receiver may return technically valid data that is not what the requester expected.

The v2.5.1 structures show QPD in QBP_Q11 - QBP - Query by parameter requesting an RSP segment pattern response, QBP_Q13 - QBP - Query by parameter requesting an RTB - tabular response, QBP_Q15 - QBP - Query by parameter requesting an RDY display response, and QBP_Q21 - QBP - Get person demographics, and 18 other message structures. That tells you where it can appear, but the implementation guide still decides which optional fields are meaningful.

For practical interface work, read the generated field panel for datatype, required, repeatable, and table details, then use the notes below to decide what the field should mean in the receiving workflow.

QPD-1 Message Query Name RequiredR SingleS TypeCE Table0471

QPD-1 names the query, event, stored procedure, virtual table, or profile being invoked. This is the semantic switch for the query, so both sides need to agree on the allowed names and their parameter rules.

QPD-2 Query Tag OptionalO SingleS TypeST

QPD-2 is the requester's handle for this query. Echoing it back correctly is what lets the requester match a response to the question it asked.

QPD-3 User Parameters (in successive fields) OptionalO SingleS Typevar

QPD-3 carries the criteria or parameters that narrow the query. Keep each parameter in the expected datatype shape and avoid relying on display text that the receiver cannot evaluate.

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