SignalEDI documentation

2. EDI Basics

What is EDI?

Electronic Data Interchange (EDI) is the computer-to-computer exchange of business documents in a standard electronic format. Instead of emailing a PDF purchase order or faxing an invoice, EDI encodes those documents in a structured text format that both sender and receiver systems can parse automatically.

EDI eliminates manual data entry, reduces errors, and is required by most large retailers (Walmart, Target, Amazon), healthcare payers (Medicare, Blue Cross), and 3PLs. If a trading partner tells you "we only accept EDI," SignalEDI is what you use to become EDI-capable.

X12 Format

ANSI X12 is the dominant EDI standard in North America. An X12 document is a flat text file with segments separated by a tilde (~) and elements within each segment separated by an asterisk (*).

ISA*00*          *00*          *ZZ*SENDERID       *ZZ*RECEIVERID     *260101*1200*U*00401*000000001*0*P*>~
GS*PO*SENDERID*RECEIVERID*20260101*1200*1*X*004010~
ST*850*0001~
BEG*00*SA*PO-2024-001**20260101~
REF*DP*DEPT-47~
N1*ST*WALMART STORE #4872*91*0001234567~
PO1*1*100*EA*24.99**BP*ITEM-001*VN*VENDOR-SKU-A~
CTT*1~
SE*8*0001~
GE*1*1~
IEA*1*000000001~

Each line is a segment. The first element (before the first *) is the segment identifier (e.g. ISA, BEG, PO1). The number after the segment ID is the element position within that segment.

Common Transaction Sets

ISA / GS Segments Explained

Every X12 interchange starts with an ISA (Interchange Control Header) segment and ends with IEA. Within each interchange, one or more GS functional groups wrap the actual transaction sets.