The ARQ (Appointment Request) segment is the heart of a schedule request message: it asks a filler application to schedule, reschedule, hold, or cancel an appointment. ARQ heads the SRM (Schedule Request Message) and carries the identifiers that tie a request to its placer and filler, the requested timing, the appointment type and duration, and the contact people involved. It is the request-side counterpart of the SCH segment that a filler returns, and it works together with the APR preferences segment and the RGS resource group within the sch-appointments group.
Purpose
ARQ states the appointment a placer wants. It identifies the request with a placer appointment ID (and, on responses or modifications, a filler appointment ID), describes the appointment by schedule, reason, type, and duration, and specifies the requested start date/time range. ARQ also records who placed the request and who entered it, with their contact details. The trigger event of the enclosing SRM message (for example S01 request new appointment, S02 request modification, S03 request discontinuation) tells the filler what action to take on the ARQ.
Used in
ARQ heads the SRM (Schedule Request Message). It is the first segment of the request and is followed by optional APR preferences and one or more RGS resource groups, each grouping resource segments (AIG/AIL/AIP/AIS).
- SRM (Schedule Request Message) — ARQ carries the request itself; trigger events S01–S05 and beyond drive the requested action.
- ARQ does not appear in SIU (Unsolicited Scheduling Information); SIU uses SCH for the filler's view. See /academy/hl7/messages/siu for the unsolicited side of scheduling.
Field-by-field reference
Source: HAPI HL7v2 v2.5.1 javadocs (ARQ javadoc) for sequence, name, data type, and repetition. Length is not published in the javadocs (—); Required and Table # are filled from the HL7 v2.5.1 standard where well-established.
| Seq | Name | Data Type | Length | Req | Repeat | Table # | Description |
|---|---|---|---|---|---|---|---|
| ARQ-1 | Placer Appointment ID | ei | — | R | — | — | Placer's unique identifier for the appointment request |
| ARQ-2 | Filler Appointment ID | ei | — | O | — | — | Filler's unique identifier for the appointment |
| ARQ-3 | Occurrence Number | nm | — | O | — | — | Occurrence within a series of repeating appointments |
| ARQ-4 | Placer Group Number | ei | — | O | — | — | Groups related appointment requests together |
| ARQ-5 | Schedule ID | ce | — | O | — | — | Identifies the schedule the request targets |
| ARQ-6 | Request Event Reason | ce | — | O | — | — | Reason the scheduling event was requested |
| ARQ-7 | Appointment Reason | ce | — | O | — | HL70276 | Reason for the appointment itself |
| ARQ-8 | Appointment Type | ce | — | O | — | HL70277 | Type or category of the appointment |
| ARQ-9 | Appointment Duration | nm | — | O | — | — | Requested duration of the appointment |
| ARQ-10 | Appointment Duration Units | ce | — | O | — | — | Units for the appointment duration |
| ARQ-11 | Requested Start Date/Time Range | dr | — | O | Y | — | Window in which the appointment should start |
| ARQ-12 | Priority-ARQ | st | — | O | — | — | Requested priority of the appointment |
| ARQ-13 | Repeating Interval | ri | — | O | — | — | Interval for a repeating appointment series |
| ARQ-14 | Repeating Interval Duration | st | — | O | — | — | Duration over which repetition occurs |
| ARQ-15 | Placer Contact Person | xcn | — | O | Y | — | Person to contact about the placer request |
| ARQ-16 | Placer Contact Phone Number | xtn | — | O | Y | — | Phone number for the placer contact |
| ARQ-17 | Placer Contact Address | xad | — | O | Y | — | Address for the placer contact |
| ARQ-18 | Placer Contact Location | pl | — | O | — | — | Location of the placer contact |
| ARQ-19 | Entered By Person | xcn | — | O | Y | — | Person who entered the request |
| ARQ-20 | Entered By Phone Number | xtn | — | O | Y | — | Phone number of the entering person |
| ARQ-21 | Entered By Location | pl | — | O | — | — | Location of the entering person |
| ARQ-22 | Parent Placer Appointment ID | ei | — | O | — | — | Placer ID of a parent appointment |
| ARQ-23 | Parent Filler Appointment ID | ei | — | O | — | — | Filler ID of a parent appointment |
| ARQ-24 | Placer Order Number | ei | — | O | Y | — | Placer order numbers linked to the request |
| ARQ-25 | Filler Order Number | ei | — | O | Y | — | Filler order numbers linked to the request |
Most-used fields
- ARQ-1 Placer Appointment ID — the required key of the request; every ARQ must carry it. It is how placer and filler correlate the request through its lifecycle.
- ARQ-11 Requested Start Date/Time Range — the requested timing window; repeats so a placer can offer multiple acceptable windows. Pairs naturally with APR time selection criteria.
- ARQ-8 Appointment Type and ARQ-7 Appointment Reason — classify the appointment so the filler can route and book it correctly.
- ARQ-9 Appointment Duration with ARQ-10 Appointment Duration Units — the requested length; always read the two together since the number is meaningless without its units.
- ARQ-4 Placer Group Number — links related requests (for example a multi-resource visit) so they are scheduled together.
Version differences (2.3 to 2.8.2)
- 2.3 — ARQ was introduced with the scheduling chapter. The early structure already covered placer/filler IDs, timing, type, duration, and contacts.
- 2.4 / 2.5 / 2.5.1 — Field set stabilized at 25 fields including the parent appointment IDs (ARQ-22, ARQ-23) and the placer/filler order numbers (ARQ-24, ARQ-25). This page documents the 2.5.1 form.
- 2.6 / 2.7 / 2.8 / 2.8.2 — ARQ retains the 25-field structure. Later versions refine component definitions of the underlying data types (EI, CE, DR) and clarify usage notes but do not add or remove ARQ fields.
The normalized takeaway: from 2.5 onward ARQ is a stable 25-field segment. Engines targeting 2.3 should confirm the presence of the order-number fields, which are most reliably available from 2.5.1.
Common mistakes
- Omitting ARQ-1. Placer Appointment ID is required. A request without it cannot be correlated and will typically be rejected.
- Splitting duration from units. Sending ARQ-9 without ARQ-10 (or vice versa) makes the duration ambiguous. Always populate both.
- Confusing ARQ with SCH. ARQ is the request (placer to filler in SRM). SCH is the filler's response/notification. Do not emit ARQ in an SIU message.
- Collapsing repeating windows. ARQ-11 repeats; placing several acceptable windows in one repetition defeats the purpose of offering alternatives.
- Treating Filler Appointment ID as required on a new request. ARQ-2 is normally assigned by the filler; a new-appointment request (S01) usually leaves it empty.
- Using the wrong trigger event. The action (new, modify, cancel) is carried by the SRM trigger event, not by a field in ARQ. Match the trigger to the intent.
Examples
Minimal
ARQ|PLAC-77821^EAST-CLINIC
Fully populated
ARQ|PLAC-77821^EAST-CLINIC|FILL-55012^EAST-CLINIC|1|GRP-3391^EAST-CLINIC|SCHED-RAD^Radiology^L|ROUTINE^Routine request^L|HEADACHE^Headache evaluation^L|MRI^MRI Brain^L|30|MIN^minutes^UCUM|20260618080000^20260618170000|R|||DRSMITH^Smith^Anna^^^^^^EAST-CLINIC|^^^^^1^555^2034567|^^^smith@east-clinic.example|EAST-CLINIC^^^EAST||CLERK01^Jones^Pat^^^^^^EAST-CLINIC|^^^^^1^555^2039999|EAST-CLINIC^^^EAST||||ORD-90011^EAST-CLINIC|
Annotated breakdown
ARQ|PLAC-77821^EAST-CLINIC|FILL-55012^EAST-CLINIC|1|...|MRI^MRI Brain^L|30|MIN^minutes^UCUM|20260618080000^20260618170000|R|...
| | | | | | | |
| | | | | | | └─ ARQ-12 Priority-ARQ (ST): R = routine priority
| | | | | | └──────────────────────────────── ARQ-11 Requested Start Date/Time Range (DR), repeating: 08:00–17:00 on 2026-06-18
| | | | | └─────────────────────────────────────────────────── ARQ-10 Appointment Duration Units (CE): minutes
| | | | └──────────────────────────────────────────────────── ARQ-9 Appointment Duration (NM): 30
| | | └─────────────────────────────────────────────────────────────────── ARQ-8 Appointment Type (CE): MRI Brain
| | └──────────────────────────────────────────────────────────────────────── ARQ-3 Occurrence Number (NM): 1
| └─────────────────────────────────────────────────────────────────────────────────────────────── ARQ-2 Filler Appointment ID (EI)
└──────────────────────────────────────────────────────────────────────────────────────────────────────────────────── ARQ-1 Placer Appointment ID (EI), REQUIRED
In context — SRM^S01 schedule request
MSH|^~&|SCHEDAPP|EAST-CLINIC|FILLER|EAST-CLINIC|20260610093000||SRM^S01^SRM_S01|MSG00231|P|2.5.1
ARQ|PLAC-77821^EAST-CLINIC||1|GRP-3391^EAST-CLINIC|SCHED-RAD^Radiology^L|ROUTINE^Routine request^L|HEADACHE^Headache evaluation^L|MRI^MRI Brain^L|30|MIN^minutes^UCUM|20260618080000^20260618170000|R
APR|^PreferredDay^Weekday~^PreferredTime^Morning|^Resource^RES-MRI-02|^Location^EAST-CLINIC|15|^AllowOverride^N
RGS|1|A|RG-MRI^MRI Group^L
AIG|1|A|RES-MRI-02^MRI Scanner 2^L|EQUIP
AIS|1|A|MRI^MRI Brain^L
In context — SRM^S02 request modification
MSH|^~&|SCHEDAPP|EAST-CLINIC|FILLER|EAST-CLINIC|20260611140000||SRM^S02^SRM_S01|MSG00244|P|2.5.1
ARQ|PLAC-77821^EAST-CLINIC|FILL-55012^EAST-CLINIC|1|GRP-3391^EAST-CLINIC|SCHED-RAD^Radiology^L|RESCHED^Patient reschedule^L|HEADACHE^Headache evaluation^L|MRI^MRI Brain^L|30|MIN^minutes^UCUM|20260620080000^20260620170000|R
RGS|1|A|RG-MRI^MRI Group^L
AIG|1|A|RES-MRI-02^MRI Scanner 2^L|EQUIP
FHIR mapping
| Source | Target | Notes |
|---|---|---|
| ARQ | Not mapped at the segment level | No segment-level ConceptMap is published in the v2-to-FHIR IG for ARQ. Scheduling data maps conceptually to the FHIR Appointment, Schedule, and Slot resources. |
Conceptually, an ARQ request corresponds to creating or updating a FHIR Appointment (with status reflecting the requested action), where the requested timing aligns with candidate Slot resources on a Schedule. The mapping is not standardized at the segment level, so engines implement it with local logic.
Engine considerations
- Enforce ARQ-1 presence on ingest; reject or quarantine requests without a placer appointment ID.
- Preserve repetitions in ARQ-11, ARQ-15, ARQ-16, ARQ-17, ARQ-19, ARQ-20, ARQ-24, and ARQ-25 — these are the repeating fields per the javadocs.
- Map the SRM trigger event to your internal action so the request is routed as new, modify, or cancel.
- Keep ARQ-9 and ARQ-10 together through transforms so duration never loses its units.
- Correlate ARQ-2 (filler ID) on responses back to the original ARQ-1 to maintain the appointment lifecycle.
How Vorro parses and produces ARQ
When parsing, Vorro reads ARQ by sequence, treating ARQ-1 as the required correlation key and exposing the repeating fields (ARQ-11 windows, the placer/entered-by contact fields, and the order-number fields) as collections. The SRM trigger event is captured alongside the ARQ so the requested action is preserved.
When producing ARQ, Vorro emits ARQ-1 first and always, pairs ARQ-9 with ARQ-10, serializes repeating windows and contacts with proper repetition delimiters (~), and aligns identifiers with the SCH segment used on the response path. Empty optional fields are left blank rather than padded. The APR and RGS segments that accompany ARQ are produced in the same message build so the request grouping stays intact.
