What Is VDA 4988? The JIT Call-Off Message Explained
Between the monthly delivery forecast (VDA 4984) and the truck at the dock stands a much sharper instrument: the JIT call-off. In the VDA recommendation family it is VDA 4988 - an EDIFACT DELJIT (Delivery Just-In-Time) profile that tells sequenced suppliers exactly what to build and ship, in production order, on a horizon of hours.
If you have ever asked why an OEM needs a different message when VDA 4984 already carries quantities and dates, this guide answers that - and explains the message your sequencing team actually lives on.
Why JIT needs its own message
VDA 4984 answers "how many parts do you need over the next weeks?" VDA 4988 answers a harder question: "which specific parts, in which exact production sequence, must arrive at which dock at which minute?" Assembly lines for seats, cockpits, bumpers or battery trays consume sequenced modules in a precise order tied to individual vehicle bodies moving down the line. The supplier does not ship to stock - it builds to sequence and must hit a delivery window measured in minutes, because the receiving line has little or no buffer.
A forecast message cannot express that: it carries quantities per date, not ordered positions per vehicle. That is the gap DELJIT - and the VDA 4988 profile built on it - was designed to fill.
What is inside a VDA 4988 message
Exact layouts vary by OEM guideline, but a VDA 4988 file combines these areas:
| Area | Typical content |
|---|---|
| Envelope | UNB/UNZ, UNH/UNT with message type DELJIT and the guideline-specified release |
| Header | Call-off identification (BGM), message date (DTM), references to the scheduling agreement (RFF), buyer / supplier / ship-to parties (NAD) |
| Line / point of use | LOC identifying the assembly line, station or unloading point the sequence belongs to |
| Item | LIN with the customer part number (PIA, IMD as in VDA 4984) |
| Sequence detail | QTY with the required quantity, DTM with the production date and time window, and RFF carrying the sequence number that ties the delivery position to a specific vehicle order |
| Logistics | Depending on the OEM: dock/transport details, container or loading-unit hints, and cumulative reconciliation figures |
The segment that matters most is the sequence reference. Two identical parts with different sequence numbers are different deliveries - they may carry different colours, trim codes or option packages. Suppliers load trucks in sequence order so the receiving line consumes boxes in exactly the order the call-off lists them.
How VDA 4988 differs from VDA 4984
| VDA 4984 (DELFOR) | VDA 4988 (DELJIT) | |
|---|---|---|
| Direction | Customer to supplier (mostly) | Customer to supplier |
| Horizon | Days to months (firm + forecast) | Hours - tied to live production |
| Granularity | Quantities per part per date | Positions per part per sequence number |
| Binding level | Firm zone + forecast zone | Firm - build and ship exactly this |
| Typical parts | All materials, incl. bulk/VMI | Sequenced modules: seats, cockpit, bumpers, trays |
| Miss a message and | Plan drifts, complaints follow | Line stops - escalation within minutes |
Who uses it
VDA 4988 is common wherever German OEMs run sequenced JIT logistics - Volkswagen Group plants are the classic case, with BMW, Mercedes-Benz and large Tier-1s operating similar DELJIT-based call-offs in their own networks. Implementations are usually tied to the OEM's own EDI portal or release-creation system, and the guideline published by that OEM is authoritative down to element level: never assume two customers' VDA 4988 files are interchangeable.
Operational rules suppliers learn the hard way
- Sequence discipline beats speed. A box that arrives early but out of sequence is as disruptive as a late one - the line scans positions in order. Load trucks in call-off order, not in picking convenience order.
- Monitor the last transmission, not the first. VDA 4988 messages supersede each other quickly; your MRP must consume the newest file completely before the next arrives, or sequence deltas get lost.
- Counters drift silently. If the OEM uses cumulative reconciliation fields, verify them per message; a 1-piece drift today is a truck-shortage escalation next week.
- Window precision is contractual. The DTM time window on a JIT call-off is not a suggestion. Delivery outside the window can mean refusal at the dock, even with the right parts.
Where validation fits in
Sequence call-offs are generated by systems, but they are also read, mapped and re-processed by yours. Every mapping change, ERP upgrade or guideline revision is a chance to break envelope integrity, date formats or code lists - and JIT tolerates errors for minutes, not days. Validating the structure of your inbound 4988 files (and your outbound 4987 despatch advices answering them) locally, before processing, is cheap insurance against a very expensive phone call from the plant.