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EDIFACT message guide · Travel and tourism

AVLREQ Availability request

The UN/EDIFACT interactive message a customer or agent sends to ask a provider about availability of a travel, tourism or leisure service.

Sent by
Customer, travel agent or booking system
Received by
Travel service provider
Standard
UN/EDIFACT · Interactive (I-EDI) message
X12 equivalent
No direct equivalent

What is the EDIFACT AVLREQ message?

AVLREQ is the UN/EDIFACT interactive travel, tourism and leisure availability request. The directory defines it as a message sent by a customer or their agent to a service provider to request availability for a travel, tourism or leisure service. The provider answers with the interactive availability response (AVLRSP).

Availability checks come before booking: the traveler or agent asks what rooms, seats or services are free for given dates, and then books one with a reservation request. Because availability changes constantly, the check is done in real time.

How the EDIFACT AVLREQ message worksDiagram of the UN/EDIFACT AVLREQ Availability request message. Customer, travel agent or booking system sends it to travel service provider. It usually starts the exchange. It is usually followed by AVLRSP. Inside the UIB and UIH envelopes, the directory D.21A requires, in the . 6 conditional segment groups are listed by their trigger segment.How the EDIFACT AVLREQ message worksAvailability request: who sends it, where it fits and what the directory marks mandatory1 WHERE IT FITSUSUALLY FOLLOWSStarts the exchangeAVLREQSENDERCustomer, travel agentor booking systemRECEIVERTravel service providerUSUALLY FOLLOWED BYAVLRSPAvailability response2 WHAT DIRECTORY D.21A REQUIRESInteractive interchangeUIB … UIZMessage AVLREQUIH … UITBODY AND SEGMENT GROUPS+ 6 conditional groups, starting with:SSRTVLTIFRTIMOVODIBlue box: mandatory segment group. Conditional groups are listed by the trigger segment that starts them; a group is sent only when its data applies.Conditional segments outside groups are not drawn.Structure: mandatory segments and groups in the UN/EDIFACT directory D.21A listing for AVLREQ. Your trading partner's implementation guide adds itsown requirements.
How the EDIFACT AVLREQ message worksDiagram of the UN/EDIFACT AVLREQ Availability request message. Customer, travel agent or booking system sends it to travel service provider. It usually starts the exchange. It is usually followed by AVLRSP. Inside the UIB and UIH envelopes, the directory D.21A requires, in the . 6 conditional segment groups are listed by their trigger segment.How the EDIFACT AVLREQmessage worksAvailability request: who sends it, where it fitsand what the directory marks mandatory1 WHERE IT FITSUSUALLY FOLLOWSStarts the exchangeAVLREQSENDERCustomer, travelagent or bookingsystemRECEIVERTravel serviceproviderUSUALLY FOLLOWED BYAVLRSPAvailability response2 WHAT DIRECTORY D.21A REQUIRESInteractive interchange (UIB … UIZ)Message AVLREQ (UIH … UIT)BODY AND SEGMENT GROUPS+ 6 conditional groups, starting with:SSRTVLTIFRTIMOVODIBlue box: mandatory segment group. Conditionalgroups are listed by the trigger segment thatstarts them; a group is sent only when its dataapplies. Conditional segments outside groups arenot drawn.Structure: mandatory segments and groups in theUN/EDIFACT directory D.21A listing for AVLREQ.Your trading partner's implementation guide adds itsown requirements.

How to read this diagram: the top row shows who sends AVLREQ, to whom, and which messages usually come before and after it. The lower part shows what the directory D.21A itself requires: the envelopes around AVLREQ and the segments and segment groups it marks mandatory. Conditional groups are listed by their trigger segment rather than drawn in full. This is the directory's minimum, not a trading partner's requirement: a message implementation guide usually makes some conditional groups mandatory, restricts the codes and may use an older directory.

Expand diagram Download SVG

When it is used

  • Checking hotel room availability for dates
  • Checking seats on a journey
  • Comparing options before booking

Where it fits in the message flow

This message AVLREQ Availability request
Usually followed by AVLRSP Availability response

Structure

Mandatory segments in AVLREQ (directory D.21A)

In UN/EDIFACT directory D.21A, the AVLREQ message has 54 segment positions arranged in 9 segment groups. These are the segments and segment groups marked mandatory at message level, in order; a mandatory group is shown with the segment that starts it. Segments inside conditional groups are needed only when the group is used. This is the directory’s requirement, not your trading partner’s: each partner’s message implementation guide names the directory it uses, often an older one such as D.96A or D.01B where the structure can differ, makes some conditional segments mandatory and restricts the codes. This structure comes from one published copy of the directory and has not been independently verified: confirm it before you build a map.

  • UIH
  • UIT

Practical example

AVLREQ in practice

A travel agent searches for a hotel in Vienna for three nights. The booking system sends several hotels an AVLREQ for the dates and room type. Each hotel answers with an AVLRSP listing available rooms and rates, and the agent books the best option with a RESREQ.

Implementation

Implementation considerations for AVLREQ

  • Design for high request volumes compared with bookings.
  • Cache cautiously, since availability changes quickly.
  • Handle timeouts gracefully without blocking the user.
  • Check which interactive standards each provider supports.

How ECOM helps

Automate AVLREQ with ECOM

Industry

Hospitality

Procurement, invoicing and supplier integration for hotels, restaurant groups and foodservice suppliers.

Solution

Batch and Real-Time Integration

Scheduled batch processing and real-time, API-driven integration on one platform.

Solution

API Integration

Connect partner and application APIs to your systems and bridge them with EDI processes.

Compare X12 and EDIFACT, or see answers to general questions in the EDI FAQ.

Related messages

Related travel and tourism messages

All 16 travel and tourism messages

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