BAK
Reports transaction purpose, acknowledgment type, purchase-order identity, and related header dates or references.
Order-acknowledgment fundamentals
What Is an EDI 855 Purchase Order Acknowledgment?
A practical guide to the X12 transaction a seller can use to respond to a purchase order.
EDI 855 is the X12 Purchase Order Acknowledgment transaction set. It can communicate BAK response context, purchase-order lines, native ACK occurrences, schedules, qualified products, parties, references, dates, contacts, notes, and related commercial evidence. Actual content varies by sender, receiver, release, and implementation agreement.
Where the 855 fits
A seller may send an 855 after receiving an 850 Purchase Order. An 856 Ship Notice or 810 Invoice may follow later, but this sequence is conceptual rather than mandatory and partner workflows differ.
LINE, ACKNOWLEDGMENT, and SUMMARY rows preserve source ownership
Each physical PO1 creates a LINE row. Each physical ACK under that line creates a distinct ACKNOWLEDGMENT row with its parent PO1 context. A transaction without PO1 or ACK detail creates one SUMMARY row. Schedules and repeatable structures remain deterministic collections rather than being flattened into an invented single response.
Common 855 structures
PO1 and PID
Identify acknowledged order lines, qualified products, quantities, prices, and descriptions.
ACK and SCH
Carry native line acknowledgment statuses and their qualified schedule evidence.
N1, REF, DTM, PER, and NTE
Carry qualified parties, references, dates, contacts, and notes without discarding repeated occurrences.
Which releases are tested?
Smart Mapping is tested for generic releases 004010, 004030, and 005010. Other releases and partner implementation references are not advertised as supported.
Common EDI 855 questions
What is the difference between an 850 and an 855?
The 850 is the buyer's purchase order. The 855 is a seller-side acknowledgment response that can carry header and line evidence about that order; it does not replace or become the original 850.
Does an 855 guarantee fulfillment?
No. BAK and ACK codes are source-reported acknowledgment evidence. Shipment, delivery, invoice, and payment outcomes require later documents or external operational facts.
What an 855 does not prove
A mapped status code does not by itself establish one overall business outcome, fulfillment result, financial total, compliance determination, or partner certification. Continue with the 855 reading guide, inspect the EDI 855 canonical data map, or open the file in the browser-local EDI Viewer.