The AIG segment describes a general resource required for an appointment that is not a person, a location, or a device with its own dedicated segment — for example a room of equipment, a kit, or any schedulable resource identified by type. It appears in scheduling (SIU) messages, repeated once per resource the appointment needs, and is grouped under the SCH segment that defines the appointment itself.
Purpose
AIG carries the identity, type, quantity, timing, and duration of a general resource booked for an appointment. Where SCH describes the appointment as a whole and AIS describes a scheduled service, AIG names a non-person, non-location resource the appointment consumes: which resource, how many, when it starts relative to the appointment, and for how long. Each AIG also carries a filler status so the scheduling system can report whether that resource is booked, pending, or cancelled.
Used in
AIG appears in SIU scheduling messages (the schedule information unsolicited family — new appointments, modifications, cancellations, and notifications). It is one of the resource segments grouped beneath SCH, alongside AIS (services), AIL (locations), and AIP (personnel).
Field-by-field reference
Source: the Vorro HL7 segment database (extracted from the official v2-to-FHIR IG). R = required (cardinality min ≥ 1). Repeat = field may repeat. Length is not carried by the FHIR source and is shown as —.
| Seq | Name | Data Type | Length | Req | Repeat | Table # | Description |
|---|---|---|---|---|---|---|---|
| AIG-1 | Set ID - AIG | si | — | R | — | — | Sequence number ordering the resource segments; usually 1. |
| AIG-2 | Segment Action Code | id | — | O | — | — | Add, update, or delete action for this resource. |
| AIG-3 | Resource ID | cwe | — | O | — | — | Coded identifier of the specific resource. |
| AIG-4 | Resource Type | cwe | — | R | — | — | The kind of resource required; the one required code. |
| AIG-5 | Resource Group | cwe | — | O | — | — | Group the resource belongs to. |
| AIG-6 | Resource Quantity | nm | — | O | — | — | How many units of the resource are needed. |
| AIG-7 | Resource Quantity Units | cne | — | O | — | — | Units the resource quantity is expressed in. |
| AIG-8 | Start Date/Time | dtm | — | O | — | — | When the resource is needed (absolute time). |
| AIG-9 | Start Date/Time Offset | nm | — | O | — | — | Resource start offset from the appointment start. |
| AIG-10 | Start Date/Time Offset Units | cne | — | O | — | — | Units for the start offset value. |
| AIG-11 | Duration | nm | — | O | — | — | How long the resource is needed. |
| AIG-12 | Duration Units | cne | — | O | — | — | Units for the duration value. |
| AIG-13 | Allow Substitution Code | cwe | — | O | — | — | Whether a substitute resource is acceptable. |
| AIG-14 | Filler Status Code | cwe | — | O | — | — | Booking status of the resource (booked, pending, etc.). |
Most-used fields
- AIG-4 Resource Type is the only required field beyond the set ID and the one schedulers branch on — it names what kind of resource the appointment needs.
- AIG-3 Resource ID pins the request to a specific resource when the type alone is not enough.
- AIG-6 Resource Quantity and AIG-7 Units express how much of the resource is reserved.
- AIG-8 Start Date/Time, AIG-9 offset, and AIG-11 Duration place the resource on the timeline relative to the appointment.
- AIG-14 Filler Status Code is how the filling application reports whether the resource is actually booked.
Version differences (2.3 to 2.8.2)
- 2.3: the appointment resource segments (AIG, AIS, AIL, AIP) were introduced with the scheduling (SIU) message family.
- 2.5: coded fields move from
CEtowardCWE/CNE; AIG-7/AIG-10/AIG-12 unit fields settle onCNE. - 2.7+: the v2-to-FHIR alignment work formalizes AIG-2 Segment Action Code semantics for add/update/delete.
- Receivers built for 2.3 ignore trailing fields and component refinements they do not recognize.
Common mistakes
- Treating AIG as a service or person segment — AIG is for general resources; use AIS for services, AIL for locations, AIP for personnel.
- Omitting AIG-4 Resource Type, the only meaningful required field, leaving the resource untyped.
- Confusing AIG-8 (absolute start) with AIG-9 (offset from the appointment start) and double-applying timing.
- Sending AIG-6 Resource Quantity without AIG-7 Units, so the quantity is ambiguous.
- Ignoring AIG-14 Filler Status Code and assuming a requested resource is booked.
Examples
Minimal valid AIG (set ID plus the required resource type):
AIG|1||^^^^MRI
Fully-populated AIG (one MRI room reserved for 30 minutes, booked):
AIG|1|A|RES001^MRI Suite 2^L|^^^^MRI||1|UNITS^units^HL70299|20260615093000|0|MIN^minutes^HL70299|30|MIN^minutes^HL70299|N|BOOKED^Booked^HL70278
Annotated breakdown of the fully-populated example (selected fields):
AIG ← segment ID
1 ← AIG-1 Set ID
A ← AIG-2 Segment Action Code (Add)
RES001^MRI Suite 2^L ← AIG-3 Resource ID
^^^^MRI ← AIG-4 Resource Type (required)
1 ← AIG-6 Resource Quantity
20260615093000 ← AIG-8 Start Date/Time
0 ← AIG-9 Start Date/Time Offset
30 ← AIG-11 Duration
MIN^minutes^HL70299 ← AIG-12 Duration Units
BOOKED^Booked^HL70278 ← AIG-14 Filler Status Code
In-context inside an SIU^S12 (new appointment), AIG following SCH:
MSH|^~&|SCHED|MERCYGEN|EHR|MERCYGEN|20260610120000||SIU^S12^SIU_S12|MSG2001|P|2.5.1
SCH|APPT0001^MERCYGEN||||||ROUTINE^Routine|||30|MIN|^^^20260615093000^20260615100000|||||REQ001
PID|1||MR12345^^^MERCYGEN^MR||DOE^JOHN^Q||19800101|M
RGS|1|A
AIG|1|A|RES001^MRI Suite 2^L|^^^^MRI||1|UNITS^units^HL70299|20260615093000|0|MIN^minutes^HL70299|30|MIN^minutes^HL70299|N|BOOKED^Booked^HL70278
In-context inside an SIU^S15 (appointment cancellation), resource released:
MSH|^~&|SCHED|MERCYGEN|EHR|MERCYGEN|20260612080000||SIU^S15^SIU_S15|MSG2045|P|2.5.1
SCH|APPT0001^MERCYGEN||||||ROUTINE^Routine|||30|MIN|^^^20260615093000^20260615100000|||||REQ001
PID|1||MR12345^^^MERCYGEN^MR||DOE^JOHN^Q||19800101|M
RGS|1|A
AIG|1|D|RES001^MRI Suite 2^L|^^^^MRI||1|UNITS^units^HL70299|20260615093000|0|MIN^minutes^HL70299|30|MIN^minutes^HL70299|N|CANCELLED^Cancelled^HL70278
FHIR mapping
Primary target resource: Appointment. AIG fields map onto the Appointment.participant structure — the resource becomes a participant actor, with its type and timing carried on the participant. Official ConceptMap: Appointment.
Key Appointment mappings:
| AIG field | FHIR target (Appointment) |
|---|---|
| AIG-3 Resource ID | participant.actor (Location.identifier) |
| AIG-4 Resource Type | participant.type (CodeableConcept) |
| AIG-8 Start Date/Time | participant.period.start |
| AIG-9 Start Date/Time Offset | participant.period.start (start + AIG-9 per AIG-10 units) |
| AIG-11 Duration | participant.period.end (participant.period.start + AIG-11) |
Fields without a published Appointment mapping (AIG-1, AIG-2, AIG-5, AIG-6, AIG-7, AIG-10, AIG-12, AIG-13, AIG-14) are sequencing, action, quantity/unit, substitution, and status details not represented on the Appointment participant.
Engine considerations
- Required in practice: AIG-1 and AIG-4 are the standard-required fields, but real interfaces also expect AIG-3 (specific resource) and AIG-14 (filler status) for usable scheduling.
- Resolve AIG-8/AIG-9/AIG-10 timing consistently — apply the offset to the appointment start only when an absolute start is absent.
- Combine AIG-6 with AIG-7 units; never trust a bare quantity.
- Honor AIG-2 Segment Action Code (add/update/delete) so resource changes across SIU events are applied, not duplicated.
- Group AIG under its RGS/SCH parent so the resource attaches to the correct appointment.
How Vorro parses and produces AIG
Vorro reads AIG within its RGS resource group and attaches each resource to the appointment defined by the parent SCH. AIG-4 Resource Type is mapped to the FHIR Appointment.participant.type, AIG-3 to the participant actor identifier, and AIG-8/AIG-9/AIG-11 are resolved into participant.period start and end. Filler status (AIG-14) and segment action (AIG-2) drive how Vorro reconciles resource state across SIU trigger events, and quantity/unit pairs (AIG-6/AIG-7) are preserved together so a downstream system never sees an unqualified number.
Related pages
- SCH — the appointment header AIG resources are grouped under.
- AIS — scheduled service segment, the service counterpart to AIG.
- SIU messages — where AIG carries appointment resources.
