The EDI 940 · Warehouse Shipping Order is the document a buyer or seller sends to a warehouse — often a 3PL — telling it exactly what to ship, to whom, and under what terms. It is not a purchase order and it is not a ship notice. The 850 · Purchase Order creates the commercial promise between buyer and seller; the 940 turns part of that promise into a physical instruction a warehouse can act on; the 945 · Warehouse Shipping Advice then reports back what the warehouse actually shipped.
If you use a third-party warehouse, the 940 is where your order stops being data in an ERP and becomes boxes on a dock. Errors here do not stay digital for long.
What is the EDI 940 · Warehouse Shipping Order?
The 940 is an X12 transaction set sent to a warehouse or distribution center directing a shipment. It identifies the ship-to party, the carrier and service level, the requested ship date, and, line by line, the items and quantities to pick.
Think of the chain it sits in:
- The 850 · Purchase Order says what the buyer ordered from the seller.
- The 940 · Warehouse Shipping Order says what the seller wants the warehouse to ship for that order.
- The 945 · Warehouse Shipping Advice says what the warehouse shipped.
- The 856 · Ship Notice / ASN tells the buyer what is coming.
- The 810 · Invoice bills for what shipped and was accepted.
When those documents agree, fulfillment is routine. When the 940 disagrees with the 850 — wrong quantity, wrong ship-to, a line that was cancelled on an 860 · Purchase Order Change — the warehouse will faithfully ship the wrong thing, on time, with perfect paperwork.
What does a 940 actually contain?
At the header, the 940 carries the warehouse instruction: the depositor (the seller whose goods are stored), the ship-to name and address, carrier and routing instructions, and any special handling or reference numbers the warehouse needs to match the shipment back to the original order.
At the line level, each item carries the product identifier — usually the buyer's item number or UPC alongside the seller's SKU — the quantity to ship, and the unit of measure. That unit-of-measure detail is where many 940s quietly fail: an order for 12 eaches sent as 12 cases is not a small error, it is a twelvefold shipment and a very expensive return.
Some implementations also carry lot, expiration, or pallet instructions, and order-level notes the pick team actually reads. A 940 that relies on a free-text note to carry a critical instruction — a different label, a retailer compliance requirement — is fragile, because notes are the first field downstream systems drop.
Why does the 940 matter if the warehouse already has a portal or API?
Because the instruction still has to be unambiguous, acknowledged, and traceable. A portal entry, an API call, and a 940 all do the same job, but the discipline is identical: the warehouse should only act on an instruction it can match to an order, confirm back with a 945, and reconcile later against the ASN and invoice.
That confirmation loop is the point most often missed. Sending a 940 and hearing nothing is not success — it is an unacknowledged instruction. Mature flows treat the 945 · Warehouse Shipping Advice as mandatory: it closes the loop on what was picked, what was short, and which carrier and tracking details apply, so the seller can build an accurate 856 and 810 instead of copying the original order forward and hoping the dock agreed.
Where do 940 flows usually break?
The first break is the stale instruction. An order changes — an 860 amends quantity or cancels a line — but the 940 already sent to the warehouse is never updated or withdrawn. The warehouse ships the original instruction correctly and everyone else calls it a warehouse error. Version discipline matters: a changed order needs a changed warehouse instruction, explicitly linked to the one it replaces.
The second break is inventory the seller assumed. The 940 instructs shipment of goods the warehouse does not have, in the lot or condition required, because the seller's available-to-promise figure and the warehouse's actual stock — the figure an 846 · Inventory Inquiry / Advice would report — had drifted apart. The result is a short pick discovered at the dock, too late to re-source calmly.
The third break is treating the 940 as a file to generate rather than a commitment to verify. If nobody checks the 945 against the 940, shortages, substitutions, and carrier changes surface only when the buyer files a claim or the invoice is disputed — weeks later, with worse evidence than the 945 offered on day one.
Frequently asked questions
Is the 940 · Warehouse Shipping Order the same as the 850 · Purchase Order?
No. The 850 is the buyer's commercial order to the seller. The 940 is the seller's fulfillment instruction to a warehouse. Different sender, different recipient, different job — the 940 exists because the party who sold the goods is often not the party holding them.
Who sends the 940 and who receives it?
The seller or brand owner sends it; the warehouse, distribution center, or 3PL holding their inventory receives it and acts on it.
What document answers a 940?
The 945 · Warehouse Shipping Advice. It reports what was actually shipped, in what quantities, and with what carrier details — the warehouse's counterpart to the seller's ASN discipline.
Does a 940 replace a warehouse's own WMS?
No. The 940 is the instruction that enters the warehouse management system; the WMS still runs picking, packing, and labeling. The EDI document is how the instruction arrives accurately and traceably, not how the dock does its work.
A warehouse will ship exactly what it is told to ship — which is why the telling has to be exact. At SignalEDI, we treat the 940/945 loop as a first-class part of the order flow, reconciled against the order and the ASN, because the cheapest fulfillment error is the instruction that gets checked before a box is taped shut.
— Chris, founder of SignalEDI
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