HL7 OVR Override Segment
HL7 field reference OVR 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
OVR records override information when a normal rule, warning, or constraint has been bypassed by an authorized workflow.
The standard describes OVR this way: This segment allows a sender to override specific receiving applications business rules to allow for processing of a message that would normally be rejected or ignored.
Equipment and specimen-control segments are used around instruments, analyzers, containers, device commands, device status, and test configuration. They are practical plumbing for lab and automation workflows.
The main trap is treating an equipment status as if it were a clinical result, or treating a specimen/container identifier as if it were interchangeable with a patient or order identifier. Keep the layers separate.
The imported v2.5.1 message-structure catalog does not list a common message structure for OVR here, so I would treat it as profile-driven. Use it when your sending and receiving systems have explicitly agreed how the segment is carried.
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.
OVR-1 qualifies the equipment or specimen workflow rather than identifying it. This is the sort of field receivers often use for branching, filtering, or display grouping.
Use the agreed value set, starting from HL7 table 0518. A local code without an agreed coding system is a small ambiguity that becomes a mapping problem later.
OVR-2 identifies the Business Rule Override Code for this equipment or specimen workflow. Send the identifier that the receiving system actually keys on, and keep the assigning authority or coding system visible when the datatype supports it.
The generated panel links this to HL7 table 0521; many real interfaces narrow that list further, so follow the receiver's implementation guide.
OVR-3 is human-readable context. Keep it useful for display and troubleshooting, but do not hide required workflow logic here unless the implementation guide explicitly says the receiver parses it.
OVR-4 identifies a person, provider, staff member, or contact involved in this equipment or specimen workflow. Use the structured name or provider datatype instead of flattening everything into display text.
OVR-5 carries Override Authorized By for this equipment or specimen workflow. Populate it only when the receiver has a clear use for it, and keep the value in the datatype shape shown in the generated field panel.