# Glossary
Source: https://www.stedi.com/docs/edi-platform/edi-essentials/glossary

***

title: Glossary
sidebarTitle: "Glossary"
------------------------

## Composite element

A single [element](#element) that contains multiple values of different types, similar to a struct or record. The [specification](#specification) will specify which fields make up a composite element. The values in a composite element are kept apart by a [delimiter](#delimiter). The delimiter to use is specified in the [interchange](#interchange) header. In the following example, values are delimited using a `:`.

```
PRV*LA***ORT:HS:Y~
```

## Delimiter

A delimiter is used in the [X12 EDI Format](#x12-edi-format) to mark the end of a [segment](#segment) or [element](#element). The end of a [segment](#segment) is [delimited](#delimiter) by a `~` and the end of an [element](#element) by a `*`. Here's an example of two segments, both with three elements.

```
SE*2*0000~
GE*1*987654321~
```

There are also delimiters for [repeated elements](#repeated-element) and [composite elements](#composite-element), but these aren't standardized. Instead, these delimiters are specified in the [interchange](#interchange).

## Element

An element is a data field within a [segment](#segment). In the [X12 EDI Format](#x12-edi-format), elements in a [segment](#segment) are delimited by a `*`. For example, here's a [segment](#segment) with several elements.

```
GS*SO*00*00*20210902*1200*987654321*X*008010~
```

The values an element may contain, are described in a [specification](#specification).

## EDI (Electronic Data Interchange)

EDI – Electronic Data Interchange – is an umbrella term for many different “standardized” frameworks for exchanging business-to-business transactions like invoices, insurance applications, train sheets, credit reports. It is often used synonymously with two of the most popular standards – [X12](#x12-edi-format), used primarily in North America, and [EDIFACT](#edifact-format), which is prevalent throughout Europe. Read more: [What makes EDI so hard?](https://www.stedi.com/blog/what-makes-edi-so-hard)

## EDIFACT format

A file format for encoding [EDI](#edi) data, standardized by United Nations/Electronic Data Interchange for Administration, Commerce and Transport (UN/EDIFACT).

## Functional group

Within an [EDI](#edi) file, a functional group is a set of [transaction sets](#transaction-set). Typically, all the [transaction sets](#transaction-set) within a functional group are intended for the same department within an organization.

The beginning of a functional group is marked by the [GS](https://www.stedi.com/edi/x12-008010/segment/GS) [segment](#segment) and the end is marked by the [GE](https://www.stedi.com/edi/x12-008010/segment/GE) [segment](#segment). A functional group must be part of an [interchange](#interchange).

## Interchange

Within an [EDI](#edi) file, an interchange is a set of [functional groups](#functional-group) which in turn contain [transaction sets](#transaction-set). Typically, the contents of an interchange is intended for a specific organization and the contents of a [functional group](#functional-group) is intended for a specific department within that organization.

The beginning of an interchange is marked by the [`ISA`](https://www.stedi.com/edi/x12-008010/segment/ISA) [segment](#segment) and the end is marked by the [IEA](https://www.stedi.com/edi/x12-008010/segment/IEA) [segment](#segment). Every EDI file must have at least one interchange and consequently, every EDI file starts with an [`ISA`](https://www.stedi.com/edi/x12-008010/segment/ISA) [segment](#segment) and ends with an [IEA](https://www.stedi.com/edi/x12-008010/segment/IEA) [segment](#segment). Read more: [Control numbers in X12 EDI](https://www.stedi.com/blog/control-numbers-in-x12-edi).

## Loop

A loop is a collection of [segments](#segment) that can appear multiple times in a [transaction set](#transaction-set). The [segments](#segment) in a loop typically have a semantic relationalship, for example, the segments [Party Identification](https://www.stedi.com/edi/x12/segment/N1), [Geographic Location](https://www.stedi.com/edi/x12/segment/N4), and [Communication Contact Information](https://www.stedi.com/edi/x12/segment/COM) together can tell you about a single [trading partner](#trading-partner) and a loop of those segments allows you to refer to multiple [trading partners](#trading-partner) in a [transaction set](#transaction-set).

In [X12 EDI Format](#x12-edi-format), there's no special [delimiter](#delimiter) for loops, nor is there a set of [segments](#segment) that mark the begin and end of the loop, like there is for [interchanges](#interchange), [functional groups](#functional-group), and [transaction sets](#transaction-set). Instead, the segments in the loop are just repeated.

```
N1*21*Stedi*ZZ*ID001~
N4*New York**US~
COM*16*stedi.com~
N1*21*Acme*ZZ*ID002~
N4*Miami**US~
COM*16*acmebread.co~
```

## Repeated element

A single [element](#element) that contains multiple values of the same type, similar to a homogeneous array. Not every [element](#element) can be repeated; the [specification](#specification) must indicate that it's okay to do so.

In [X12 EDI Format](#x12-edi-format), the values in a repeated element are kept apart by a [delimiter](#delimiter). The delimiter to use is specified in the [interchange](#interchange) header. In the following example, values are delimited using a `/`.

```
AAA*Y***NF/NR/TO~
```

## Repeated segment

Within an [EDI](#edi) file, some segments can occur multiple times in a row. The [specification](#specification) will tell when a segment can be repeated.

In [X12 EDI Format](#x12-edi-format), a repeated segment appears as, well, a segment that's repeated.

```
NTE**When a segment has need to repeat,~
NTE**How does one accomplish that feat?~
NTE**It's really no bother.~
NTE**One after the other.~
NTE**A solution that's simple and neat.~
```

## Segment

Within an [EDI](#edi) file, a segment is a set of [elements](#element), where the segment is like a record and the [elements](#element) are its fields. Each segment starts with a segment identifier that tells you which [elements](#element) will follow. The different types of segments and their elements are listed in the [specification](#specification).

In the [X12 EDI Format](#x12-edi-format), segments are [delimited](#delimiter) by a `~`. It's also common to add a new line character after the [delimiter](#delimiter), but that's for human readability only and has no semantic value.

## Specification

A specification describes the data schema of a [transaction set](#transaction-set). It lists the [loops](#loop) and [segments](#segment), the order in which they appear, and the [elements](#element) within the [segments](#segment). The specification gives you all the information you need to write or interpret an [EDI](#edi) document that conforms to that specification.

[X12](#x12) has published [many specifications](https://www.stedi.com/edi). A [trading partner](#trading-partner) can use these specifications directly, or they can base their own specification on one of them. Find popular EDI specifications in [the Stedi Network](https://www.stedi.com/edi/network).

## Trading partner

Any business that sends or receives business transactions.

## Transaction set

A transaction set is a type of business document, for example a purchase order, or a booking cancellation. Each transaction set is based on a [specification](#specification) that describes what data the transaction set can and must contain. There is a [list of standardized transaction sets](https://www.stedi.com/edi).

The standard transaction sets are designed to be widely applicable. A [trading partner](#trading-partner) can take a transaction set, base its own [specification](#specification) on it, and only accept the data it knows how to handle. Many of these [business-specific transaction sets are available on Stedi](https://www.stedi.com/edi/network).

## X12

An organization that develops and maintains the [X12 EDI](#x12-edi-format) standards.

## X12 EDI Format

A file format for encoding [EDI](#edi) data, standardized by [X12](#x12). It's text-based and makes use of [delimiters](#delimiter) to mark the [segments](#segment) and [elements](#element).