ANSI X.12 (formally ASC X12, the Accredited Standards Committee X12) is the dominant North American EDI standard family. Maintained by the American National Standards Institute since 1979, it defines hundreds of standardized transaction sets covering virtually every B2B document type — purchase orders, invoices, shipping notices, healthcare claims, and customs filings.
Customs-relevant X.12 transaction sets include:
- 309 — Customs Manifest (used in AMS for vessel cargo manifests)
- 350 — Customs Status Information (CBP responses to filings)
- 353 — Customs Events Advisory Details (CBP advisories to filers)
- 355 — Customs Acceptance/Rejection
- 357 — Customs Insufficient Information
- 358 — Customs Consist Information (rail)
- 359 — Customs Customs Summary Information
- 361 — Carrier Interchange Agreement
- 426 — Reliability Data
- 810 — Invoice (broadly used in B2B)
- 850 — Purchase Order
- 856 — Advance Ship Notice (ASN) (broadly used in supply chain)
Each transaction set has a defined structure of segments and elements with strict syntax. Versions are released periodically (003040, 004010, 005010 are common in customs); newer versions add fields and refine validation but are largely backward-compatible for legacy fields.
X.12 is used in U.S. customs filing because CBP selected it as the basis for ABI and AMS when those systems were first built in the 1980s, and the standard has remained in place through the ACE migration.
Outside North America, the equivalent role is played by EDIFACT.