BEG

Beginning Segment for Purchase Order. The first business segment of the 850 Transaction Set — it declares what kind of PO is being issued.

Definition

In the ANSI ASC X12 specification, BEG is the beginning segment of the 850 (Purchase Order) Transaction Set header. It carries the framing parameters of the order:

• BEG01 — Transaction Set Purpose Code (element 353): 00 Original, 01 Cancellation, 04 Change, 05 Replace, 07 Duplicate.
• BEG02 — Purchase Order Type Code (element 92): NE New order, BK Blanket order, CR Consignment, DS Drop ship, SA Stand alone.
• BEG03 — Purchase Order Number (element 324): the issuer's PO number.
• BEG04 — Release Number (element 328): release call against an open order.
• BEG05 — Date (element 373): order date (CCYYMMDD).
• BEG06 — Contract Number (element 367): linked master contract, optional.

Origin

BEG has been in X12 since version 003010 of the ANSI ASC X12 standard (1989). The structure is stable; recent versions (008010 and beyond) have only added 353 and 92 codes. Official steward: ASC X12, ANSI-accredited since 1979.

Example in context

Opening a Transaction Set 850 (standard order):

Reading: ST opens transaction set 850, BEG declares an original (00) new order (NE), number PO-12345, no release, dated 14 May 2026. REF carries the contract number.

Related terms

• ST — the transaction set opener preceding BEG.
• SE — the symmetric closing of the transaction set.
• PO1 — the order lines.
• REF — supplementary references.