ST

Transaction Set Header. The mandatory opener of every X12 Transaction Set — it tells what kind of message begins and assigns it a control number.

Definition

In the ANSI ASC X12 standard, ST is the first segment of every Transaction Set. Structure:

• ST01 — Transaction Set Identifier Code (element 143): 3-digit code of the message type — 850 Purchase Order, 810 Invoice, 856 Ship Notice/Manifest, 855 PO Acknowledgment, 997 Functional Acknowledgment, 270 Eligibility Inquiry (healthcare), 820 Payment Order/Remittance Advice.
• ST02 — Transaction Set Control Number (element 329): unique number for the Transaction Set within its functional group. Must match SE02.
• ST03 — Implementation Convention Reference (element 1705, from 005010 HIPAA): reference to the active IC version, used mainly by HIPAA Transaction Sets (270/271/834/835/837).

Origin

ST has been in X12 since version 002001 (1985). It is via ST01 that the receiver knows which parser to apply to the rest of the message. Maintained by ASC X12, under the X12.5 Interchange Control Structures standard.

Example in context

Reading: ST declares a Transaction Set 850 (Purchase Order), control number 0001. SE on closure echoes 0001.

Related terms

• SE — the symmetric closer of the Transaction Set.
• GS — the enclosing sub-envelope.
• BEG — the business header of the 850.
• ISA — the interchange envelope.