EDI packets are dense with acronyms, but the underlying ideas are ordinary business paperwork given strict shapes. Work through the groups below in order — documents first, then connections, then compliance — and click through to the free tools wherever a term has one. Start with the plain-English EDI guide if you want the narrative version first.
Core documents
850 — Purchase Order
The buyer's formal order: items, quantities, prices, ship-to, dates. Inspect samples in the 850 viewer.
855 — Purchase Order Acknowledgement
The supplier's reply accepting, changing, or rejecting the 850's lines.
856 — Advance Ship Notice (ASN)
The carton-level packing list sent ahead of the trailer, keyed by SSCC barcodes. Validate samples in the 856 validator.
810 — Invoice
The payment request referencing the PO and shipment. Check samples in the 810 validator.
820 — Payment Order / Remittance Advice
Payment instruction and remittance detail telling the supplier which invoices a payment covers.
997 — Functional Acknowledgement
A syntax-level receipt confirming a transmission arrived intact — not a business approval.
999 — Implementation Acknowledgement
A deeper receipt reporting acceptance or rejection against the implementation guide, with error locations.
940 — Warehouse Shipping Order
Instructs a warehouse to pick, pack, and ship goods to a destination.
945 — Warehouse Shipping Advice
Confirms goods shipped from the warehouse, closing the 940 instruction.
846 — Inventory Inquiry / Advice
Reports on-hand inventory levels so buyers plan orders against real stock.
860 — Purchase Order Change
Amends a previously sent 850 — quantities, dates, or ship-to details.
865 — Purchase Order Change Acknowledgement
Confirms receipt and disposition of an 860 change request.
204 — Load Tender
A shipper's offer of freight to a carrier: origin, destination, equipment, and dates.
990 — Load Tender Response
The carrier's accept-or-decline answer to a 204 tender.
214 — Shipment Status
In-transit milestones (picked up, departed, delivered) reported against the tender.
GS1-128 shipping label
The barcode label format carrying the SSCC (and often PO and carton data) that receiving scans against the ASN.
Healthcare documents
837 — Healthcare Claim
The claim submission providers send to payers for services rendered. Background in the 837 claims guide.
835 — Remittance Advice
The payer's payment explanation: what was paid, adjusted, or denied. See the 835 guide.
270 / 271 — Eligibility Request / Response
The 270 asks whether a patient is covered; the 271 answers. See the eligibility guide.
276 / 277 — Claim Status Request / Response
Tracks a submitted claim through payer adjudication without phone calls.
278 — Referral / Authorization
Requests and reports prior authorization for services requiring payer approval.
Document structure
ANSI X12
The North American EDI standard defining segment structures for 300+ transaction sets. Convert samples with the X12-to-JSON tool.
EDIFACT
The UN-backed international EDI standard, dominant outside North America.
Segment
One line (record) of an X12 document, e.g. ST, BIG, or N1 — segments compose the document.
Data element
A single field inside a segment, separated by the element delimiter (usually *).
Loop
A repeating group of segments, e.g. one loop per line item on a purchase order.
ISA — Interchange Control Header
The envelope header identifying sender, receiver, and control numbers for the whole interchange.
GS — Functional Group Header
Groups one type of transaction (e.g. all 850s) inside an interchange.
ST / SE — Transaction Set Header / Trailer
The brackets around a single document, carrying its type code and control number.
Control number
The unique sequence identifier (ISA13, GS06, ST02) used to track and deduplicate interchanges.
Qualifier
A code explaining what an adjacent identifier means — e.g. which numbering scheme an ID belongs to.
Implementation guide
A partner's profile of the standard: which segments are mandatory, which codes are allowed, and what passing looks like.
Connections and transport
AS2
Encrypted, signed HTTP messaging with per-message delivery receipts (MDNs) — the dominant retail transport. Compared with SFTP in our AS2 vs SFTP guide.
SFTP
Secure file transfer over SSH to agreed server folders — simpler, schedule-driven, no native receipt.
VAN (Value-Added Network)
A third-party mailbox hub that stores, forwards, and often bills per-document EDI traffic.
MDN
Message Disposition Notification — the signed AS2 receipt proving exact bytes arrived intact.
ISA ID
The sender/receiver identifiers in the ISA envelope — your address on the EDI network.
Mailbox
A partner-specific inbox/outbox on a VAN or platform where files wait for pickup.
Webhook
An HTTPS callback your system receives when a document validates, routes, or gets acknowledged.
Integration approaches
Web EDI
A browser portal for reading orders and keying documents manually — ideal at low volumes. Compared with APIs in EDI API vs Web EDI.
EDI API
Programmatic document exchange (usually JSON over HTTPS) with X12 translation handled by the platform. Start at the API quickstart.
Mapping
Defining how your internal fields correspond to the partner's required EDI layout. Preview the concept in the mapping tool.
Translation
Converting between formats — JSON to X12 outbound, X12 to JSON inbound. Try the JSON-to-X12 converter.
Validation
Checking a document against the standard and the partner's guide before sending. Run the free EDI validator.
Onboarding (partner)
The setup sequence — packet review, identifiers, mapping, test files, certification — before live exchange. See the onboarding guide.
Certification
The partner's formal approval after reviewing your test documents, required before go-live.
Compliance and operations
Chargeback
A retailer penalty for non-compliant documents or shipments — late ASNs, bad labels, missing SSCCs.
Scorecard
A partner's periodic grade of your ASN accuracy, on-time rates, and fill performance.
SSCC
Serial Shipping Container Code — the unique barcode identifying each carton or pallet in the ASN.
GS1 / UPC / GTIN
Global product-identification standards: GTINs identify items, UPCs carry them at retail, GS1 governs the system.
HIPAA (transactions)
The US law mandating standard electronic healthcare transactions and their privacy/security handling. See HIPAA and EDI.
BAA
Business Associate Agreement — the contract required before a vendor touches protected health information.
Trading partner
Any organization you exchange EDI with — retailers, distributors, payers, 3PLs.
Mandate (partner)
A partner's requirement that suppliers transact via specified EDI documents and transports.
Test file
A sample document exchanged during certification to prove compliance before live traffic. Exercise them in the EDI test lab.
Go-live
The switch from certification to production exchange. Developers follow the go-live checklist.
Requirements review
Reading the partner packet for documents, identifiers, and test evidence before configuring anything. Use the requirements checker.
Cost model
The twelve-month equation — subscription, partners, usage, implementation, support — used to compare vendors. Model it with the cost calculator.
EDI software cost
What SMB EDI actually costs across plans and workloads, with published evidence. See the 2026 pricing guide.
X12 viewer
A readable rendering of raw X12 segments for debugging. Open the X12 viewer.