X12-LOOP

X12 loop is an X12 concept designating a group of repeatable segments that models an entity (line, party, lot) inside a Transaction Set.

Definition

An X12 loop is a syntactic container with no explicit opening/closing segment. The loop starts at a key segment (LIN, IT1, PO1, NM1) and ends when the next key segment or a higher-level segment appears. Loops can be nested (loop 2300 contains loop 2400 in 837).

Origin

Concept present since the first X12 version (1983). Loop-numbering nomenclature is codified in ASC X12 guides and HIPAA TR3 documents.

Use

In a HIPAA 837: loop 2000A (Billing Provider HL), 2000B (Subscriber HL), 2000C (Patient HL), 2300 (Claim), 2400 (Service Line). Each loop opened by an HL or LX carries dozens of segments.

Related terms

• X12 — the parent standard.
• HL (X12) — hierarchical opener.
• X12 segment IDs — base syntax.
• Conformance level — nesting level.