Electronic Data Interchange
The Interchange Header (UN/EDIFACT)

The Interchange Header is the starting control segment of the interchange envelope.  After the recipient has received the document, the interchange header is the first data segment encountered in the document.  The interchange header contains:

• the sender and receiver information,
• authorization and security information,
• date and time interchange was prepared,
• standard version of interchange structures, and
• the control number that uniquely identifies the interchange.

This topic covers:

• Interchange Header in a Document
• Programmatically Reading the Interchange Header
• Programmatically Generating the Interchange Header

Interchange Header in a Document

In the document, the interchange header is identified with the first letters "UNB" followed by the element separator.

The interchange header data stream fit into the implementation guideline defined for the interchange header as follows:

REF		ELE		NAME		REQ		TYPE	MIN/MAX	VALUE	COMMENT
01		S001		Syntax Identifier		M					Composite element indicating the Syntax Version.
	01		0001		Syntax Identifier		M	A	4/4	UNOB	This value indicates UN/ECE Syntax Level B is used in the interchange.
	02		0002		Syntax Version Number		M	AN	1/1	4	This value indicates Syntax Version 4 is used  in the interchange.
02		S002		Interchange Sender		M					Composite element identifying the sender of the interchange.
	01		0004		Interchange Sender Identification		M	A	4/4	SENDERID	This value is the identity of the sender.  Its meaning is qualified by the associated component element 0007.
	02		0007		Partner Identification Code Qualifier		C	AN	1/1	ZZ	This element qualifies element 0004.  The value "ZZ" indicates that the sender identification at 0004 is mutually defined which means it only has meaning to the trading partner.
03		S003		Interchange Recipient		M					Composite element identifying the recipient of the interchange.
	01		0010		Recipient Identification		M	A	4/4	RECIPIENTID	This value is the identity of the recipient. Its meaining is qualified by the associated component element 0007.
	02		0007		Partner Identification Code Qualifier		C	AN	1/1	ZZ	This element qualifies element 0010.  The value "ZZ" indicates that the recipient identification at 0010 is mutually defined which means it only has meaning to the trading partner.
04		S004		Date and Time of Preparation		M					Composite element indicating the date and time the interchange was prepared.
	01		0017		Date		M	AN	8/8	20090419	The date the interchange was prepared.
	02		0019		Time		M	AN	4/4	1230	The time the interchange was prepared.
05		0020		Interchange Control Reference		M		AN	10/10	1	Unique control number assigned to the interchange.
06		S005		Recipient Reference/Password Details		C					Composite element indicating the date and time the interchange was prepared.
	01		0022		Recipient Reference/Password		M	A	1/14	MYPASSWORD	The date the interchange was prepared.
	02		0025		Recipient Reference/Password Qual		M	AN	2/2	BB	The time the interchange was prepared.
07		0026		Application Reference		C		AN	1/14	INVOIC	This value is used to aid processing of the interchange by some application, department, etc.
08		0029		Processing Priority Code		C		A	1/1	A	The value "A" is a predefined code that indicates that the interchange is to be processed with highest priority.
09		0031		Acknowledgment Request		C		N	1/1	1	The value "1" is a predefined code that requests acknowledgment of interchange when it is received.
10		0032		Interchange Agreement Identifier		C		AN	1/35		No value is assigned but present to keep data elements that follow it and have value to maintain their position in the segment.
11		0035		Test Indicator		C		N	1/1	1	The value "1" is a predefined code that indicates the interchange is for testing only.

Programmatically Reading the Interchange Header

The following steps demonstrates how to read the interchange header.

• Create an instance of ediDocument.

  Dim oEdiDoc As Fredi.ediDocument

  Set oEdiDoc = New Fredi.ediDocument
  

• Load the schema.

  Dim oSchemas As Fredi.ediSchemas
  Dim oSchema As Fredi.ediSchema
  
  ' Disable standard reference library.
  Set oSchemas = oEdiDoc.GetSchemas
  oSchemas.EnableStandardReference = False
  
  Set oSchema = oEdiDoc.LoadSchema(App.Path & "\EDIFACT_INVOIC.SEF", Schema_Standard_Exchange_Format)

• Load the document.

  ' Load EDI document normally.
  oEdiDoc.LoadEdi App.Path & "\SampleEdifactDoc.EDI"
  
  

• Get the first interchange.

  Dim oInterchange As Fredi.ediInterchange
  
  ' Get first interchange.
  Set oInterchange = oEdiDoc.FirstInterchange
  
  

• Get the interchange header and read elements

  ' Get interchange header.
  Dim oHeader As Fredi.ediDataSegment
  Dim oElements As Fredi.ediDataElements
  Dim oElement As Fredi.ediDataElement
  Dim sResult As String
  Dim i As Integer
  
  Set oHeader = oInterchange.GetDataSegmentHeader
  
  ' Get elements collection.
  Set oElements = oHeader.DataElements
  
  sResult = ""
  
  For Each oElement In oElements
  

  Dim oSubElements As Fredi.ediDataElements
  Dim oSubElement As Fredi.ediDataElement
  
  Set oSubElements = oElement.DataElements
  
  If oSubElements.Count > 0 Then

  ' Read component elements.
  sResult = sResult & vbTab & oElement.ID & vbCrLf
  
  For Each oSubElement In oSubElements

  sResult = sResult & vbTab & vbTab & oSubElement.ID & " = " & oSubElement.Value & vbCrLf
  
  

  Next
  
  

  Else

  sResult = sResult & vbTab & oElement.ID & " = " & oElement.Value & vbCrLf
  
  

  End If
  

  Next
  

Programmatically Generating the Interchange Header

The following steps demonstrates how to generate the interchange header.

• Create an instance of ediDocument.

  Dim oEdiDoc As Fredi.ediDocument

  Set oEdiDoc = New Fredi.ediDocument
  

• Load the schema.

  Dim oSchemas As Fredi.ediSchemas
  Dim oSchema As Fredi.ediSchema
  
  ' Disable standard reference library.
  Set oSchemas = oEdiDoc.GetSchemas
  oSchemas.EnableStandardReference = False
  
  Set oSchema = oEdiDoc.LoadSchema(App.Path & "\EDIFACT_INVOIC.SEF", Schema_Standard_Exchange_Format)

• Specify the terminators.

  ' Specify the terminators to use on the document.
  oEdiDoc.SegmentTerminator = "'" & vbCrLf
  oEdiDoc.ElementTerminator = "+"
  oEdiDoc.CompositeTerminator = ":"
  oEdiDoc.ReleaseIndicator = "?"
  

• Create the interchange.  The CreateInterchange method creates the interchange entity including the interchange header and trailer control segment.

  Dim oInterchange As Fredi.ediInterchange
  
  ' Create the Interchange envelope.
  Set oInterchange = oEdiDoc.CreateInterchange("UN", "D08A")

• Set the values in the interchange header.

  Dim oHeader As Fredi.ediDataSegment
  
  ' Get the interchange header.
  Set oHeader = oInterchange.GetDataSegmentHeader
  
  ' Set the values of the elements.
  oHeader.DataElementValue(1, 1) = "UNOB"
  oHeader.DataElementValue(1, 2) = "4"
  oHeader.DataElementValue(2, 1) = "123"
  oHeader.DataElementValue(2, 2) = "ZZ"
  oHeader.DataElementValue(3, 1) = "00123"
  oHeader.DataElementValue(3, 2) = "01"
  oHeader.DataElementValue(3, 3) = "ABC123"
  oHeader.DataElementValue(4, 1) = "20090419"
  oHeader.DataElementValue(4, 2) = "1230"
  oHeader.DataElementValue(5) = "1"
  oHeader.DataElementValue(7) = "INVOIC"
  oHeader.DataElementValue(11) = "1"