User Guide > Designing and Executing Processes > HL7 Integration Schemas > HL7 Segment Library
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HL7 Segment Library
A segment is a logical grouping of data fields. Message segments may be required or optional. They may occur only once in a message or they may be allowed to repeat. Each segment is given a name. For example, the ADT message may contain the following segments: Message Header (MSH), Event Type (EVN), Patient ID (PID), and Patient Visit (PV1).
Each segment is identified by a unique three-character code known as the segment ID.
All segment ID codes beginning with Z are reserved for locally defined messages. No such codes are defined within the HL7 Standard.
Name
Value
ITEM
Field ID Number
NAME
Field Name
DT
Data Type
SEQ
Sequence Number
OPT
Option: O=Optional, R=Required, C=Conditional
LEN
Size of the field
REPEAT
Number of times a field can repeat. An integer or N = No repeat. Y = indefinite or site-determined number of times.
Last modified date: 12/03/2024