Message type

Schedule information unsolicited

Delivers unsolicited scheduling information including new appointments, modifications, and cancellations. The SCH segment carries the appointment details and AIS, AIG, AIL, AIP segments define associated resources. Scheduling displays and reminder systems consume this.

23segments

8required

2groups

v2.9HL7 version

# Zato
from zato.hl7v2 import HL7Message

# An incoming message ..
raw = 'MSH|^~\&|SENDER|FAC|RCV|DEST|20260701||' \
      'SIU^S12^SIU_S12|MSG001|P|2.9\r' \
      'SCH|SCH001||||||||30|MIN|^^30^20260701\r' \
      'PID|1||MRN-10045||SMITH^JOHN||19850315|M'

# .. parsed into a Python object ..
msg = HL7Message.parse(raw)

# .. whose fields we can now access.
schedule_id = msg.sch.placer_appointment_id
duration = msg.sch.appointment_duration
name = msg.pid.patient_name
dob = msg.pid.date_time_of_birth

Python examples

Build and parse SIU^S12 messages in Python

How to construct, send, receive, and extract fields from real-world SIU^S12 messages.

Parse an incoming SIU^S12 message

Demonstrates receiving and extracting key fields from a schedule information unsolicited transaction

# Zato
from zato.hl7v2 import HL7Message

# An incoming message ..
raw = 'MSH|^~\&|SENDER|FAC|RCV|DEST|20260701||' \
      'SIU^S12^SIU_S12|MSG001|P|2.9\r' \
      'SCH|SCH001||||||||30|MIN|^^30^20260701\r' \
      'PID|1||MRN-10045||SMITH^JOHN||19850315|M'

# .. parsed into a Python object ..
msg = HL7Message.parse(raw)

# .. whose fields we can now access.
schedule_id = msg.sch.placer_appointment_id
duration = msg.sch.appointment_duration
name = msg.pid.patient_name
dob = msg.pid.date_time_of_birth

Tutorials

Learn by building

Step-by-step guides for working with HL7 v2 in Zato.

MLLP

Receive and parse HL7 v2 messages

Set up an MLLP channel, parse incoming messages, and respond with acknowledgments.

Start tutorial Build

Build and send HL7 v2 messages

Construct HL7 v2 messages from scratch using typed segment classes and send them over MLLP.

Start tutorial

FAQ

Frequently asked questions

Use the HL7v2 message parser to extract the typed structure. The parsed message gives you direct access to every segment and field by name.

from zato.hl7v2 import HL7Message

raw = 'MSH|^~\&|SENDER|FACILITY|RECEIVER|DEST|20260401120000||SIU^S12^SIU_S12|MSG00001|P|2.9\rSCH|APPT-3001|APPT-3001||||ROUTINE^Routine follow-up|ROUTINE|MINUTE^15|15|MIN|^^^20260415090000^20260415091500\rTQ1|1||BID'
msg = HL7Message.parse(raw)

schedule_id = msg.sch.placer_appointment_id
duration = msg.sch.appointment_duration

Beyond the mandatory MSH header, the required segments are: SCH, PID, RGS, AIS, AIG, AIL, AIP. Optional segments provide additional detail when available.

Zato connects to any system that speaks HL7v2 over MLLP or FHIR over REST. This includes Epic, Cerner, Meditech, Allscripts, and other EHR platforms.

Yes, Zato has built-in MLLP support for sending and receiving HL7v2 messages. MLLP channels handle the framing protocol automatically.

Zato supports HL7 v2.9, which is backward compatible with earlier versions including v2.3, v2.5, and v2.7. Standard segments and datatypes are available as typed Python classes.

Yes. Zato handles both HL7v2 and FHIR natively, so you can parse v2 messages and build FHIR resources with IG-specific extensions in the same service. Typed Python classes are available for both protocols, including extensions from US Core, UK Core, Da Vinci, and other Implementation Guides.

Reference

SIU^S12 segment composition

Segments that make up the SIU^S12 message, in order. Groups are shown with their child segments.

#	Segment	Usage	Repeats	Description	Group
1	`MSH`	Required	No	Message header	-
2	`ARV`	Optional	Yes	Access restriction	-
3	`SCH`	Required	No	Scheduling activity information	-
4	`TQ1`	Optional	Yes	Timing / quantity	-
5	`NTE`	Optional	Yes	Notes and comments	-
6	`PID`	Required	No	Patient identification	PATIENT
7	`PD1`	Optional	No	Patient additional demographic	PATIENT
8	`PRT`	Optional	Yes	Participation information	PATIENT
9	`PV1`	Optional	No	Patient visit	PATIENT
10	`PV2`	Optional	No	Patient visit - additional info	PATIENT
11	`PRT`	Optional	Yes	Participation information	PATIENT
12	`OBX`	Optional	Yes	Observation result	PATIENT
13	`PRT`	Optional	Yes	Participation information	PATIENT
14	`DG1`	Optional	Yes	Diagnosis	PATIENT
15	`RGS`	Required	No	Resource group	RESOURCES
16	`AIS`	Required	No	Appointment information - service	RESOURCES
17	`NTE`	Optional	Yes	Notes and comments	RESOURCES
18	`AIG`	Required	No	Appointment information - general resource	RESOURCES
19	`NTE`	Optional	Yes	Notes and comments	RESOURCES
20	`AIL`	Required	No	Appointment information - location resource	RESOURCES
21	`NTE`	Optional	Yes	Notes and comments	RESOURCES
22	`AIP`	Required	No	Appointment information - personnel resource	RESOURCES
23	`NTE`	Optional	Yes	Notes and comments	RESOURCES

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