EDIFACT Envelope Structure And Levels
There are two EDIFACT Envelope levels in which messages may be transmitted. The use of a particular level designates which character set will be used:
- EDIFACT Envelope LEVEL A (UNA): only upper case; only printable characters
- EDIFACT Envelope LEVEL B (UNB): upper and lower case; includes non-printing characters for delimiters
UNA: The purpose of this segment is to define the delimiters and terminators, if UNA is not used the default in the UNB segment will be used. UNB: Identifies the sender and receiver of the transmission, the date, time and the control number this is similar to the ISA segment in X12.
UNG / UNE: These segments are only used if the interchange carries multiple types of documents. If the interchange contains only one type of document then UNG/UNE are not necessary. This can be compared to the GS/GE segments in X12, but in X12 they must be sent either way.
UNZ: This is the trailer record of the transmission. The control number here must match the control number in UNA. This is similar to the ISA/IEA.
UNH/UNT: The actual transaction is between the UNH/UNT segments, similar to ST/SE in X12.
More about EDIFACT Envelope mapping
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