Written and maintained by CASRAI Editorial Board
Last updated
Short answer
An EDI 850 is the Purchase Order transaction set: the electronic message a buyer sends a supplier to place an order for goods or services. Its published purpose text says it should not be used for purchase order changes or acknowledgements. In a punchout setup, the cart and prices travel in a different message, and the order itself can travel as a cXML purchase order instead of an 850.
This page is general procurement education for lab and clinic buyers and administrators. It is not legal, financial or clinical advice, and it does not describe any particular supplier’s ordering terms.
What an EDI 850 is, and what it is not
The X12 purpose statement, as reproduced in a trading partner’s published 850 implementation guide (X12 version 4010, document version 1.0, dated 14 August 2014), describes the Purchase Order Transaction Set (850) as the format and data contents for placing purchase orders for goods and services within an Electronic Data Interchange environment. It then adds a boundary: the transaction set “should not be used to convey purchase order changes or purchase order acknowledgment information.”
That boundary is the part most explainers skip. The 850 starts an exchange; it is not the message that changes an order, and it is not the supplier’s reply. For the rest of the cycle, see our guide to the EDI 856 advance ship notice, which notes that an 850 is the order that starts the exchange, and the EDI term for medical supply procurement, which summarises the 850, 810 and 856 messages.
The 850 segment skeleton
A transaction set is built from segments. A trading partner’s published 850 guide (X12 version 4010) shows this shape:
- Envelope: ISA and GS open the interchange; GE and IEA close it.
- Heading: ST opens the transaction set; BEG is the Beginning Segment for Purchase Order; N9 carries references; N1, N3 and N4 carry names and addresses.
- Detail: PO1 is Baseline Item Data and repeats for each line (the guide allows the loop to repeat up to 100,000 times); PID describes the product or item; DTM carries dates.
- Summary: CTT carries transaction totals; SE closes the set.
One reconciliation rule from the same guide is useful to a receiving clerk or integration owner: the number of line items (CTT01) is the accumulation of the number of PO1 segments, and if a hash total (CTT02) is used, it is the sum of the quantities ordered (PO102) across the PO1 segments. The guide marks PO102 as required. Each segment in the guide is marked “Must use” or “Used”, which shows that a partner’s guide decides which segments it actually requires.
Punchout catalog, cXML order or EDI 850: how the order reaches the supplier
A punchout catalog lets a buyer shop on the supplier’s own website from inside the buyer’s procurement software. The cXML User’s Guide (version 1.1, Ariba, June 2000) separates that shopping from the order. The guide dates from 2000 and describes cXML 1.1, so treat the table as a description of the original design.
| Message | Role in the flow |
|---|---|
| PunchOutSetupRequest | Sent by the procurement application to start a punchout session when the user clicks a punchout item. |
| PunchOutSetupResponse | The supplier’s reply, containing a URL where the user shops on the supplier’s website. |
| PunchOutOrderMessage | Sent from the supplier’s website at check out, with product details and prices, back to the procurement application. |
| OrderRequest (cXML purchase order) | The purchase order, sent by the procurement application through the e-commerce hub in cXML. Acknowledging receipt means, in the guide’s words, you have “effectively booked the order.” |
| EDI 850 | The X12 purchase order transaction set: one of the order routing methods, alongside fax and e-mail, that the cXML guide contrasts with cXML routing. |
The practical consequence is in the guide’s advice for punchout-enabled suppliers: the order routing method should be cXML, because the supplier cookie “does not easily map to other order routing methods such as fax, e-mail, or EDI.” So a punchout supplier and an EDI 850 trading partner can be two different routes to the same outcome, and the route is agreed with the supplier rather than assumed.
The step before either message is internal. A purchase requisition versus a purchase order explains why the requisition is a request and the purchase order is the commitment sent to the supplier.
EDI purchase order versus an e-procurement system
An EDI purchase order is a message format. An e-procurement system, which the cXML guide calls the procurement application, is the software where requisitions and approvals happen and from which the order is sent. The two are not alternatives: the software can send the order as a cXML OrderRequest or hand it off in another routing method the supplier supports. For the wider vocabulary, see procurement versus purchasing.
What to ask a trading partner for
A pre-go-live checklist for a trading partner conversation:
- The partner’s own published 850 implementation guide, with each segment marked “Must use” or “Used”.
- The X12 version and the guide’s version and date. The example guide here is X12 4010, version 1.0, 14 August 2014.
- Whether the supplier is punchout-enabled and, if so, which cXML version and order routing method it uses. The cXML guide above is version 1.1 from 2000.
- How changes and acknowledgements are sent, since the 850 purpose text excludes both.
Common misunderstandings
The 850 can carry order changes
The purpose text says it should not be used to convey purchase order changes or acknowledgements.
The punchout cart is the order
The PunchOutOrderMessage returns product details and prices to the procurement application at check out. The purchase order is a separate step in the guide’s description.
Every partner implements the 850 the same way
The example guide marks segments as “Must use” or “Used” for that partner, so requirements are set per partner guide.
FAQ
Is an EDI purchase order the same as an EDI 850?
In X12 terms, yes: the 850 is the Purchase Order Transaction Set.
Does a punchout catalog use the 850?
The cXML guide recommends cXML order routing for punchout-enabled suppliers; an 850 applies where the partners exchange orders as EDI.
What does eprocurement mean for healthcare supply buyers?
The mechanics above (requisition, punchout session, purchase order message) are general to e-procurement. Our EDI in medical supply procurement entry covers the supply-side vocabulary.
Sources
- Ariba, Inc., cXML User’s Guide, version 1.1, June 2000: https://xml.cxml.org/schemas/cXML/1.1.010/cXMLUsersGuide.pdf (checked 3 November 2026).
- cXML.org home page: https://cxml.org/ (checked 3 November 2026).
- Cardinal Glass Industries, 850 Purchase Order, X12/V4010/850, version 1.0, 14 August 2014, a trading partner’s published implementation guide: https://www.cardinalcorp.com/wp-content/uploads/2023/01/Technical-Guide-850PurchaseOrder-Version4010.pdf (checked 3 November 2026).
