EDI 856: The Advance Ship Notice (ASN), Explained in Depth
The EDI 856 is the Advance Ship Notice, almost always called the ASN. The supplier sends it when goods ship, so the buyer knows exactly what is coming, how it is packed, and when it will arrive - before the truck reaches the dock. Of all the common EDI documents, the 856 has the most distinctive structure, and it is the one that trips up newcomers most often.
Why the ASN matters
A good ASN turns receiving from a slow, manual count into a fast, scan-based process. When a shipment arrives, warehouse staff can scan a pallet or carton label and instantly see what should be inside, compare it against the ASN, and flag discrepancies on the spot. Many large retailers depend on the ASN for cross-docking, where goods move straight from inbound to outbound without being stored, which only works if the retailer knows the contents in advance.
Because the ASN is so operationally important, large buyers often enforce it strictly. Late, missing, or inaccurate ASNs commonly trigger compliance chargebacks - financial penalties deducted from what the buyer pays the supplier. An accurate 856 is not just good practice; it directly affects the supplier's bottom line.
The hierarchical structure: the heart of the 856
What makes the 856 different from almost every other transaction is its use of HL (Hierarchical Level) loops. Rather than a flat list, the ASN describes a nested tree that mirrors how the shipment is physically organized. A very common pattern is:
- Shipment - the entire load (HL level code
S) - Order - each purchase order within the shipment (
O) - Pack - cartons or pallets (
P) - Item - the products inside each pack (
I)
This is often abbreviated as the "SOPI" structure. Each HL segment carries its own ID and a pointer to its parent, which is how the tree is assembled. The pattern is flexible: some ASNs use Shipment-Order-Item without packs, others add tare (pallet) levels. The HL design lets the same transaction model many physical packing arrangements.
How HL linking works
Consider these HL segments:
HL*1**S~ HL*2*1*O~ HL*3*2*P~ HL*4*3*I~
The first element is the HL's own number; the second is its parent's number; the third is the level code. So HL 1 is the shipment (no parent). HL 2 is an order whose parent is HL 1. HL 3 is a pack whose parent is the order. HL 4 is an item inside that pack. Read together, they build the shipment-order-pack-item tree.
Other key segments
BSN - Beginning Segment for Ship Notice
Opens the ASN with a shipment identifier, date, and time. BSN*00*SHIP12345*20240220*1430 means an original ship notice, shipment SHIP12345, dated 2024-02-20 at 14:30.
TD1, TD5, TD3 - Carrier and transport details
TD1 gives packaging and weight, TD5 gives the carrier and routing, and TD3 gives equipment (trailer or container) details.
MAN - Marks and Numbers
Carries the shipping label barcode values, such as the SSCC-18 on a pallet or carton. This is what warehouse scanners read to match a physical package to the ASN.
SN1 - Item Detail (Shipment)
At the item level, SN1 states the quantity shipped. SN1**100*EA means 100 each shipped for that item.
CTT and SE
CTT provides hierarchical-level totals for control, and SE closes the transaction.
A simplified worked example
ST*856*0001~ BSN*00*SHIP12345*20240220*1430~ HL*1**S~ TD5*B*2*UPSN~ HL*2*1*O~ PRF*PO-99831~ HL*3*2*I~ LIN**UP*012345678905~ SN1**100*EA~ CTT*3~ SE*10*0001~
In plain English: shipment SHIP12345 went out on 2024-02-20 at 14:30 via UPS. It contains one order, PO-99831, which includes 100 units of the item with UPC 012345678905.
Common pitfalls when reading an 856
- Losing track of the hierarchy. Because the meaning of an SN1 or LIN depends on which HL it sits under, reading the ASN out of context is easy to get wrong. A viewer that shows the structure helps a lot.
- Mismatched ASN and physical shipment. If the ASN says 100 but 96 arrive, the receiving scan flags a shortage. ASN accuracy is everything.
- Label values not matching MAN. If the SSCC on the carton does not match the MAN segment, scan-based receiving breaks down.
The 856's nesting is hard to follow by eye. Paste it into the viewer and see the hierarchy, carrier, and quantities laid out clearly, with a plain-English summary. Nothing is uploaded.
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