EDIFACT UNB segment: interchange header.

The UNB segment opens an EDIFACT interchange. It contains the syntax identifier and version, sender identification (with qualifier), recipient identification (with qualifier), preparation date and time, and the interchange control reference. Every UNB must have a matching UNZ at the end of the interchange.

Tag: UNB
Full name: Interchange header
Part of the message: Interchange envelope
Data elements: 11

A UNB segment, explained

Hover any part of the segment to see what it is. Open What your system receives to see the JSON or XML CleanEDI delivers.

UNB+UNOA:2+9322000000456:ZZ+9311000000123:ZZ+260823:0900+CTRL-001'

UNBInterchange header

Interchange from 9322000000456 to 9311000000123, prepared 23 August 2026 at 09:00. Control reference CTRL-001.

UNB: Interchange header
UNOA: Level A: uppercase letters and digits (syntax character set)
ZZ: Mutually agreed (sender id type)

{
  "envelope": {
    "tradingPartnerId": "9322000000456",
    "tradingPartnerIdType": "mutuallyAgreed",
    "recipientId": "9311000000123",
    "preparedAt": "2026-08-23T09:00",
    "interchangeReference": "CTRL-001"
  }
}

Example shape. In production the field names and structure follow your own API contract.

UNB structure

Elements are separated by + and their parts by :. Positions match the explainer, so 2.3 is the third part of the second element.

Position	Element	Parts
1	Syntax	1.1 Character set, 1.2 Syntax version
2	Sender	2.1 ID, 2.2 ID type
3	Recipient	3.1 ID, 3.2 ID type
4	Prepared	4.1 Date (YYMMDD), 4.2 Time (HHMM)
5	Interchange control reference	Single value
6	Recipient password	Single value
7	Application reference	Single value
8	Processing priority	Single value
9	Acknowledgement request	Single value
10	Agreement ID	Single value
11	Test indicator	Single value

Syntax: Character set (1.1)

Code	Meaning
`UNOA`	Level A: uppercase letters and digits
`UNOB`	Level B: upper and lower case
`UNOC`	ISO 8859-1 (Latin-1)
`UNOD`	ISO 8859-2 (Latin-2)
`UNOW`	UTF-8
`UNOY`	ISO 10646 (Unicode)

Sender: ID type (2.2)

Code	Meaning
`1`	DUNS number
`14`	GS1 Global Location Number (GLN)
`30`	ISO 6523 organisation ID
`ZZZ`	Mutually agreed
`ZZ`	Mutually agreed

Recipient: ID type (3.2)

Code	Meaning
`1`	DUNS number
`14`	GS1 Global Location Number (GLN)
`30`	ISO 6523 organisation ID
`ZZZ`	Mutually agreed
`ZZ`	Mutually agreed

Common EANCOM and UN/EDIFACT values. Your trading partner's implementation guide is the final word on which codes they send.

Questions

UNB segment FAQ

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Explain my message

What is the UNB segment in EDIFACT?

UNB is the Interchange Header segment. The UNB segment opens an EDIFACT interchange. It contains the syntax identifier and version, sender identification (with qualifier), recipient identification (with qualifier), preparation date and time, and the interchange control reference. Every UNB must have a matching UNZ at the end of the interchange.

What are the common UNB syntax: character set codes?

UNOA means level a: uppercase letters and digits; UNOB means level b: upper and lower case; UNOC means iso 8859-1 (latin-1); UNOD means iso 8859-2 (latin-2); UNOW means utf-8; UNOY means iso 10646 (unicode).

Where does UNB appear in an EDIFACT message?

UNB belongs to the interchange envelope part of a message, alongside UNA.

How do I read a UNB segment in my own message?

Paste the message into the free CleanEDI explainer. It breaks every UNB segment into its elements, translates the codes and shows the JSON and XML your system would receive. Nothing you paste leaves your browser.

1.1	Syntax: Character set	`UNOA`Level A: uppercase letters and digits
1.2	Syntax: Syntax version	`2`
2.1	Sender: ID	`9322000000456`
2.2	Sender: ID type	`ZZ`Mutually agreed
3.1	Recipient: ID	`9311000000123`
3.2	Recipient: ID type	`ZZ`Mutually agreed
4.1	Prepared: Date (YYMMDD)	`260823`
4.2	Prepared: Time (HHMM)	`0900`
5	Interchange control reference	`CTRL-001`