EDI Envelope Segments — ISA, GS, GE, IEA

Overview

Every EDI transaction is wrapped in envelope segments. These are consistent across all transaction types (846, 850, 856, 810).

ISA ─── Interchange Header (outermost envelope)
 GS ─── Functional Group Header
  ST ─── Transaction Set Header
  ... transaction content ...
  SE ─── Transaction Set Trailer
 GE ─── Functional Group Trailer
IEA ─── Interchange Control Trailer

ISA - Interchange Header

Delimiter Troubleshooting

• Standard delimiters: segment terminator ~, element separator *, sub-element separator > (ISA16). This is what Flxpoint's outbound documents (850, 855, 856, 810) use. Exception: the 997 reuses the delimiters of the file it acknowledges, terminator and trailing whitespace included.
• Invalid terminator (Flxpector TOK-003): if the character after ISA16 is the replacement character U+FFFD (shown as � in some editors) or a raw control byte such as 0x85, the file went through an encoding conversion that corrupted it. Every segment ends with it and most receivers reject the file. Flxpector's "Apply fix" rewrites the terminator to ~. If the file is a Flxpoint-generated 997, contact support@flxpoint.com with the file attached so it can be re-issued, and switch your own outbound terminator to ~ so the next 997 does not inherit the problem.
• Common issue: files have line breaks (CR/LF) before ~ — Flxpoint's parser handles this, but be aware
• Unusual delimiters: if a vendor uses | instead of *, the ISA header must declare it correctly at the fixed position
• Data containing delimiters: if product names or descriptions contain *, ~, or >, this will break the parser. These characters must be escaped or removed from data fields.

ISA ID Qualifier Codes (ISA05/ISA07)

X12 defines 30+ qualifier codes but FLX typically uses ZZ.

GS - Functional Group Header

GS01 Functional Identifier Codes

Accepted Versions (GS08)

Flxpoint accepts three variants:

• 004010VICS — preferred (matches VICS-specific segments)
• 004010 — accepted with a warning (not hard-rejected even if VICS-specific segments are present)
• 005010 — accepted

ISA15 Usage Indicator — Test Mode

• P = Production
• T = Test — both are processed by Flxpoint, but the UI (and Flxpector) badges test files with a "Test Mode" pill so they are not mistaken for live orders.

GE - Functional Group Trailer

IEA - Interchange Control Trailer

Control Number Matching Rules

FLX Envelope Requirements vs Generic X12

Test vs. Production traffic

Two levers distinguish test from production interchanges:

Go-live checklist: flip ISA15 T→P; switch to the production IDs on BOTH sides at the same time (a one-sided switch means files stop being recognized); keep ISA13 incrementing — never reuse control numbers across the cutover; send one small production file and confirm it processes before full volume. A "missing trading partner profile" notice from a VAN after the switch means the production IDs aren't provisioned on the receiving side yet.