Order-acknowledgment reading guide
How to Read an EDI 855 Purchase Order Acknowledgment
Follow transaction boundaries, BAK identity, line ownership, native ACK occurrences, schedules, and qualified supporting evidence.
Read an 855 from the envelope into each purchase-order line and native acknowledgment occurrence. Confirm ST01=855, use BAK for transaction-level context, then keep every ACK and SCH with the PO1 that physically owns it.
Start with ISA, GS, ST, and SE
The ISA declares separators and bounds the interchange; GS bounds the group; ST/SE bound the transaction. Control numbers and segment counts should be reviewed with their matching openers. Exact ST01=855 identifies this family.
Use BAK as source transaction context
BAK can report a purpose code, acknowledgment type, purchase-order number and date, acknowledgment date, seller order number, and release number. These are source values; a code label aids reading but does not manufacture an overall acceptance decision.
Keep each ACK with its parent PO1
PO1 establishes line context and qualified product pairs. Every physical ACK becomes its own ACKNOWLEDGMENT row and inherits parent aliases only for orientation. Native ACK status, quantity, unit, dates, and products remain distinct evidence. SCH belongs to its PO1 owner, not to the nearest ACK. Orphan ACK structure is reported rather than attached to a guessed line.
Preserve qualifier and repeat boundaries
N1 parties, REF references, DTM dates, PER contacts, NTE or MSG notes, product pairs, and commercial structures can repeat. Keep each occurrence, qualifier, source segment index, pair ordinal, and mechanism. Do not merge identical values that occur at different physical sources.
Read, parse, or convert locally in the browser
Open the EDI Viewer for readable canonical rows, the EDI Parser for mapping inspection, or the EDI Converter for CSV, XLSX, JSON, and canonical-row XML. Use the EDI 855 field reference to trace each row back to its BAK, PO1, ACK, or schedule source. Source EDI content is processed in the browser and is not uploaded as conversion input.