X12 EDI Glossary of Terms

Transaction

A transaction defines an exchange of information involving multiple parties. Loops and segments define entities contained within a transaction. X12 EDI standard provides a schema for each transaction. It mandates the order of the loops and how many times loops repeat.

For example, an “837” transaction represents submitting a medical claim from a provider to an insurer. A transaction of type “835” represents a payment of a previously submitted healthcare claim.

A complete list of all transactions (transaction sets) can be found here.

Loop

A group of segments (simple entities) that are logically related. For example, all segments related to a billing provider (a provider’s name, address and so on) are grouped in a billing provider loop.

Loops can optionally repeat.

Segment

A basic logical entity, such as a name, an amount or a reference number. Consists of multiple fields (elements), such as a first name, a last name or a postal code. Many segments also contain a qualifier field that defines the purpose of a segment.

Segments are always grouped into loops.

Element

An elementary field such as an amount or a string. Provides building blocks for segments. Could be of string, numeric and date/time type.

Elements always appear inside segments or inside other elements (composite elements).

Professional Claim (837P)

“Professional” EDI transactions are used by all providers that are not hospitals. That is, doctors, physicians, physical therapists, etc., will all use this transaction type to submit their bills. Key segments include billing provider and patient/subscriber info, diagnosis codes, provided services and charges.

Institutional Claim (837I)

“Institutional” EDI transactions are used by hospitals. Key segments include billing provider and patient/subscriber info, diagnosis codes, provided services and charges, admission and discharge information. Institutional claims typically use special codes and code sets to describe charges and services, such as revenue and “type of bill” codes, occurrence codes and others.