Electronic Data Interchange
The Group Trailer (UN/EDIFACT)

The Group Trailer ends transmission of the group envelope.  It contains:

• the number of messages or packages encapsulated in the group envelope, and
• the matching control number of associated group header pair.

This topic covers:

• Group Trailer in a Document
• Programmatically Reading the Group Trailer
• Programmatically Generating the Group Trailer

Group Trailer in a document

In the document the group trailer is identifier by it segment identifier "UNZ" followed by the data element separator.

The group trailer data stream fit into the implementation guideline defined for the group trailer as follows:

REF	ELE	NAME	REQ	TYPE	MIN/MAX	VALUE	COMMENT
01	0060	Group Control Count	M	N	1/6	1	This value indicates the number of messages or packages that are enveloped by the group at the time that it was prepared.
02	0048	Group Reference Number	M	AN	1/14	1	This is the control number that associates the group trailer with its group header pair that has a matching reference number.

Programmatically Reading the Group Trailer

The following steps demonstrates how to read the group trailer.

• 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.X12"
  
  

• Get the first interchange containing the group.

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

• Get the first group in the interchange.

  Dim oGroup As Fredi.ediInterchange
  
  ' Get first group.
  Set oGroup = oInterchange.FirstGroup

• Get the group trailer and then the read elements.

  ' Get group header.
  Dim oTrailer As Fredi.ediDataSegment
  Dim oElements As Fredi.ediDataElements
  Dim oElement As Fredi.ediDataElement
  Dim sResult As String
  Dim i As Integer
  
  Set oTrailer = oGroup.GetDataSegmentTrailer
  
  ' Get elements collection.
  Set oElements = oTrailer.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 Group Trailer

The following steps demonstrates how to generate the group 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 & "\SampleINVOICE.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 group header and trailer control segment.

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

• Create the group in the interchange.  The CreateGroup method creates the group entity including the group header and trailer control segment.

  Dim oGroup As Fredi.ediGroup
  
  ' Create the Group envelope.
  Set oGroup = oInterchange.CreateGroup("D08A")

• Set the values in the group trailer.  Although the values of the elements in the group trailer can be modified, it is not necessary.  The values are automatically populated with the correct values when the document is saved.

  Dim oTrailer As Fredi.ediDataSegment
  
  ' Get the group header.
  Set oTrailer = oGroup.GetDataSegmentTrailer
  
  ' Set the values of the elements.