What is the consequence of treating expected fields that were not included in a segment?

When expected fields are not included in a segment, they are treated as present but with null values. This approach ensures that data integrity is maintained by allowing systems that process HL7 messages to recognize that a value was anticipated but is not available. In HL7 data processing and message handling, fields that are defined as expected need to follow the schema, and while the absence of data may suggest a gap, the system acknowledges their intended presence by placing a null value in their stead.

This treatment is essential for downstream processing and validation because it allows applications to recognize that an expected field should still be taken into account, albeit with no data provided. If these fields were simply omitted or resulted in an error, it could complicate data exchanges or lead to disruptions in workflows that assume all specified fields are accounted for in their logic. Thus, setting these fields as present and null maintains the overall structure and facilitates proper handling of the message.