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EDIFACT

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United Nations/Electronic Data Interchange For Administration, Commerce and Transport (UN/EDIFACT) is the international EDI standard developed under the United Nations. The work of maintenance and further development of this standard is done through the United Nations Centre for Trade Facilitation and Electronic Business (UN/CEFACT) under the UN Economic Commission for Europe, in the Finance Domain working group UN CEFACT TBG5. EDIFACT has been adopted by the International Organization for Standardization (ISO) as the ISO standard ISO 9735.

The EDIFACT standard provides:

  • a set of syntax rules to structure data
  • an interactive exchange protocol (I-EDI)
  • standard messages which allow multi-country and multi-industry exchange

Example

See below for an example of an EDIFACT message used to answer to a product availability request: 

UNA:+.? '
UNB+IATB:1+6XPPC+LHPPC+940101:0950+1'
UNH+1+PAORES:93:1:IA'
MSG+1:45'
IFT+3+XYZCOMPANY AVAILABILITY'
ERC+A7V:1:AMD'
IFT+3+NO MORE FLIGHTS'
ODI'
TVL+240493:1000::1220+FRA+JFK+DL+400+C'
PDI++C:3+Y::3+F::1'
APD+74C:0:::6++++++6X'
TVL+240493:1740::2030+JFK+MIA+DL+081+C'
PDI++C:4'
APD+EM2:0:1630::6+++++++DA'
UNT+13+1'
UNZ+1+1'

The UNA segment is optional. If present, it specifies the special characters that are to be used to interpret the remainder of the message. There are six characters following UNA in this order:

  • component data element separator (: in this sample)
  • data element separator (+ in this sample)
  • decimal notification (. in this sample)
  • release character (? in this sample)
  • reserved, must be a space
  • segment terminator (' in this sample)

The special characters in the sample UNA segment above are also the default values.

Component data element separator and data element separator are the "first level" and "second level" separators of data elements within a message segment. Referring to them as + and : for brevity, the + separates top-level or composite data elements, and : separates second-level data elements nested within composite data elements. Trailing empty (or null) data elements and their leading separators are omitted to reduce message size.

Decimal notification is used to separate the integer from the decimal part of non-integer numbers.

Release character (analogous to the \ in regular expressions) is used as a prefix to remove special meaning from the separator, segment termination, and release characters when they are used as plain text.

Segment terminator indicates the end of a message segment.

Note: The line breaks after each segment in this example have been added for readability. There are typically no line breaks in EDI data.

UNH+1+PAORES:93:1:IA'- This is the header segment which is required at the start of every message. This code specifies that the message name and version is PAORES 93 revision 1 and it was defined by the organisation IA (IATA).

IFT+3+NO MORE FLIGHTS' - This is an "Interactive Free Text" segment containing the text "NO MORE FLIGHTS".

UNT+13+1' - This is the tail segment. It indicated that the message sent contains 13 segments.

Structure

EDIFACT has a hierarchical structure where the top level is referred to as an interchange, and lower levels contain multiple messages which consist of segments, which in turn consist of composites. The final iteration is an element which is derived from the United Nations Trade Data Element Directory (UNTDED); these are normalised throughout the EDIFACT standard.

A group or segment can be mandatory (M) or conditional (C) and can be specified to repeat. For example : 

- C99 indicates between 0 and 99 repetitions of a segment or group
- M99 signifies between 1 and 99 repetitions of a segment or group

A group, like a message, is a sequence of segments or groups. The first segment or group beneath a group must be mandatory, and the group should be made conditional if the logic of the situation demands it. 

        Service String Advice     UNA  Optional
 +----- Interchange Header        UNB  Mandatory
 | +---   Functional Group Header   UNG  Conditional
 | | +-     Message Header            UNH  Mandatory
 | | |        User Data Segments             As required
 | | +-     Message Trailer           UNT  Mandatory
 | +---   Functional Group Trailer  UNE  Conditional
 +----- Interchange Trailer       UNZ  Mandatory

Current state of EDIFACT

There is a challenge between XML and EDIFACT. Size is one issue: an equivalent XML message has a larger file size than an EDIFACT message. XML is easier to read and more flexible. More tools exist to work with XML data than with EDIFACT. EDIFACT messages can be as much as one tenth the size of XML messages. That makes XML less attractive for very high volume applications.

While EDIFACT is the preferred syntax to use in high volume bi-lateral connections or within closely knit communities, XML is appearing as the syntax of choice for reaching a wider and more disparate set of customers. EDIFACT can therefore easily create high returns in situations where close cooperation and coordination is possible. XML on the other hand is the syntax of choice for companies and governments that want to move all documents over to electronic form. XML promises the advantage of lower setup cost (no customisation) and therefore enables all customers to connect, similar to email.

EDIFACT still has the advantage of availability of agreed message contents (that need to be customized for every connection), while XML is moving towards more simple, robust specifications that can be used as-is. RosettaNet is one of the emerging XML standards and is widely used in semiconductors and high tech industries. CEN BII based on UBL is emerging as the public procurement standard of choice in the EU market, see PEPPOL.

UBL is another, currently being adopted by Scandinavian governments as a legally required standard for sending invoices to governments. It was enforced in February 2005 that all invoices to the Danish government must be sent in an electronic format.

ebXML is another XML standard built by UN/CEFACT (along with EDIFACT), and is often seen as a standard best suited for small and medium companies.

However, EDIFACT is likely to remain the most widely used in high volume, customized connections like high tech, civil aviation, retail and tourism industries, due to the amount of software that leverages the standard, and the need for integration between new systems and legacy systems.[citation needed]

Europe has a large EDIFACT installed base because it adopted the technology early, while the Asian region adopted B2B in later implementations and is therefore using more XML standards.

See also

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