What is EDI?
EDI stands for Electronic Data Interchange, and it means your store's computer and your vendor's computer exchanging standard business documents, like purchase orders, ship notices, and invoices, in an agreed format with nobody re-keying lines off a printout, no fax, and no typed-into-a-portal duplicate entry. In North America, most of those documents follow the ANSI ASC X12 standard, which assigns every document type a number called a transaction set, and the three numbers you will hear most at the counter are the 850, the 856, and the 810.
If you've ever had a distributor's shipment show up with a packing slip that matched what arrived but not what you thought you ordered, you've felt the problem EDI exists to solve. Instead of each side keeping its own version of the paperwork, both systems read the same document, so the order you sent, the shipment the vendor packed, and the invoice they sent all trace back to one set of line items. Think of it as the weekly truck's paperwork riding ahead of the truck, so the receiving half of your day starts halfway done.
Here are the X12 transaction sets a supply store is likely to run into, with their official names:
| Number | Official X12 name | What it means for your store |
|---|---|---|
| 850 | Purchase Order | The purchase order you send to a vendor |
| 855 | Purchase Order Acknowledgment | The vendor confirming what they will ship, flagging shorts and backorders |
| 856 | Ship Notice/Manifest | The advance ship notice (ASN), listing what is on the truck |
| 810 | Invoice | The vendor's bill for what shipped |
| 820 | Payment Order/Remittance Advice | Payment and remittance details |
| 832 | Price/Sales Catalog | Catalog, cost, and price updates from the vendor |
| 846 | Inventory Inquiry/Advice | What the vendor has in their warehouse |
| 860 | Purchase Order Change Request - Buyer Initiated | Changes to a purchase order you already sent |
| 997 | Functional Acknowledgment | Confirmation the file arrived and was readable |
Stores connect in a few ways: through the distributor integrations built into their point of sale, through a value-added network (VAN) or an AS2 connection that carries X12 files between trading partners, or through a web EDI portal from a service provider. Many large distributors also exchange flat item, price, and shipment files alongside X12 documents or in place of them, which is why "EDI" at a buying show often means "electronic ordering" in general.
You don't need to memorize the table. You need to know that when a vendor says "we do EDI," there's a follow-up question worth asking: which documents, and with whom. That comes up again below.
The documents in the order they happen
The easiest way to understand EDI is to walk a weekly order from your desk to the back door. Say it's Monday morning and you're building the week's replenishment for your hardware distributor.
The 850 goes out first. That's your purchase order, sent straight from your point of sale system to the vendor in X12 format, with your item numbers, quantities, and ideally your cost on each line. No printing, no portal, no reading numbers off a screen into another screen.
Soon after, a 997 usually comes back. This one is easy to overread: it confirms the vendor's system received the file and could read it. It does not mean anyone has agreed to ship anything. It's the postal carrier saying the letter arrived, not the recipient answering it.
The 855, where a vendor supports it, is the more useful reply. That's the purchase order acknowledgment, where the vendor confirms what they'll fill and flags what's shorted or going on backorder, so you know before truck day that the 3/8-inch lag bolts aren't coming.
Then, before or as the truck rolls in, the 856 arrives. Officially it's the Ship Notice/Manifest, but everyone calls it an advance ship notice, or ASN, and it lists what shipped: cartons, items, quantities. On a good setup, receiving becomes "select the shipment, confirm the quantities" instead of starting from a blank sheet and a pile of boxes. You still count, because the 856 says what the vendor says they shipped, not what's on the truck.
The 810 is the invoice, arriving as data after the shipment. Because it references the same purchase order, your system can match the invoice against what you ordered and what you received, which is how you catch being billed for twelve cases when ten came off the truck.
Two more run in the background week after week. The 832 carries catalog and price updates, so a cost change arrives as data rather than a printed price list someone has to walk through by hand. And the 846 can tell you what the vendor has sitting in their warehouse, which matters when you're deciding whether to wait on a restock or source elsewhere.
What a store gets out of it
The first gain is the most boring and the biggest: nobody re-keys the order. Say your weekly order to a hardware distributor runs 42 lines, and typing each line into a vendor portal takes about 30 seconds, part number, quantity, unit of measure, double-check. That's roughly 21 minutes of typing, before you count the errors, and it produces nothing you didn't already have in your system. (That's an illustration, not an industry statistic; your order may be longer or shorter.) Sending the 850 from the POS turns those 21 minutes into a review and a click.
The second gain is that your cost is on the order. When the purchase order carries your pricing, you and the vendor are working from the same numbers, and cost disputes get settled at order time instead of at statement time.
The third is receiving. When the 856 pre-fills the receipt, the person at the back door is verifying instead of transcribing, which is faster and catches more, because discrepancies stand out against an expected list.
The fourth is price maintenance. When the 832 brings cost changes in as data, the store can review them and push retails through on a schedule, rather than discovering in June that the February price list never made it off the break-room table. Finally, when item mapping is set up right, units of measure stop being a quiet source of bad counts, which brings us to the part where things go wrong.
What can go wrong
EDI fails in predictable places, and knowing them saves you a bad first month.
Item mapping is the big one. The vendor's item number has to map to your SKU, and where it doesn't, the line either errors out or, worse, lands on the wrong item. A vendor's catalog of 40,000 items won't line up one to one with the 8,000 you carry, so the question is what happens to the lines that don't map: do they queue for a human to fix, or do they silently drop? If you're sorting out identifiers generally, the guide on what a SKU is versus a UPC is a good companion.
Units of measure are the classic. The vendor sells you a box of 4, you sell eaches, and if the mapping treats one box as one each, your on hand is off by a factor of four until the next inventory count finds it. This is worth its own read, and we have one: units of measure, buying by the roll and selling by the foot.
The 856 that doesn't match the truck is why you still count. The advance ship notice is the vendor's statement of what shipped, and pallets get shorted, substituted, and mislabeled between the vendor's dock and yours. Receiving against the ASN is faster, but it's a starting point, not a verdict.
Price files that update cost but not retail are the slow leak. The 832 flows in, your cost rises, and nobody touches the shelf tag, so the difference comes out of margin one $12.40 box of screws at a time. The fix is a review step, not a person: someone, or something, has to look at cost changes and decide what happens to retail before the update posts.
What to ask a POS vendor
When a POS vendor tells you they "support EDI," that phrase covers everything from a single live document with a single distributor to a full catalog, ordering, and receiving pipeline. The questions that separate the two:
- Which of my vendors are live? Not "in progress," not "on the roadmap." Live, with stores running on them today. Ask by name, because your distributor list is the whole ballgame.
- Which documents per vendor? An 850 alone gets ordering off the portal. An 856 and 832 on top of it get receiving and price maintenance off your desk. The answer is usually different per vendor, and that's normal.
- Does my pricing go on the order? If your cost isn't on the 850, you lose one of the main benefits.
- Does an ASN pre-fill receiving? You want to hear that the 856 loads as a receipt you confirm, not a report you read.
- How are price changes reviewed? Look for a review queue where cost changes wait for approval, with the option to adjust retail at the same time.
- What happens when an item doesn't map? A good answer involves a work queue. Be suspicious of "that never happens."
For the wider picture of how ordering, receiving, and invoicing fit together, the purchase order process guide walks the whole cycle.
How Rundoo handles it
Rundoo is the AI-first POS for independent supply stores, and its distributor connections do the same jobs these documents do, vendor by vendor. With Orgill, purchase orders transmit over a secure EDI connection with your pricing on the order, and when Orgill ships, the shipment notification loads into Rundoo with line items and quantities in place, so receiving means selecting the shipment and confirming quantities. Price changes, warehouse inventory files with discontinuation flags, and item maintenance updates flow in behind that. House-Hasson is live with catalog loads, EDI purchase order transmission, automatic receiving from shipment notifications, and price changes. Blish-Mize is live with catalog loads including warehouse availability, EDI ordering with your pricing on the order, automatic receiving, price changes, and item maintenance. AllPro and Lancaster both have EDI 850 ordering live, and with Lancaster, catalog loads, receiving from advance ship notices, and automatic price updates are in progress.
For vendors without EDI, purchase orders can still go out by email or print, so the small regional vendor who answers the phone with "yep, we got it" stays in the same workflow as the big distributors. The current status of each connection lives in the distributor integrations guide, and the Orgill setup specifically is covered in ordering from Orgill. If you want to see it against your own vendor list, the partners page is the place to start.
