EDI Transmission Structure (EDI Documents)
EDI transmission structure can contain a single document or multiple documents, commonly referred to as “Transaction Sets”. These transaction sets are enclosed by “Header” segments and “Trailer” segments. These header and trailer segements make up the EDI “Envelope” for addressing the documents to and from trading partners (EDI transmission). The records between the header and trailer segments are called “Data Segments”. The Data Segments contain small units of information called “Elements”. An element can be made up of alpha or numeric values that can be a single character or multiple characters in length. The length of these elements and type of element is determined by the standards committee and is defined in the appropriate EDI Standard Manual for EDI transmission.
Elements within a data segment will have a relative value to the segment. For example, a segment named DTM is a date segment; thus all elements will have a relationship to a date. The following information will further define the header and trailer segments in an EDI transmission.
The “Header” is made up of the following 3 segments; the ISA segment, the GS segment, the ST segment.
The ISA segment identifies the sender and receiver of the EDI transmission. The ISA is used to begin an “Interchange” of one or more GS segments, also known as “Functional Groups”.
The GS segment identifies the application type for the interchange for both sender and receiver. This segment can be used to route EDI data to various systems or locations by trading partners (ex: different A/P systems, different physical locations). The GS segment is also the beginning of a functional group. This segment is also used to provide control information.
The ST segment identifies the type of document you are sending or receiving during EDI transmission. This segment is the beginning of the dcoument, or transaction set. For ANSI X.12 documents, the document is identified by the 3 digit numeric value assigned by the ANSI standards committee (ex: 997).
The “Trailer” is made up of the following 3 segments; the SE segment, the GE segment, the IEA segment.
The SE segment identifies the end of the document or transaction. This segment will include a total quantity of “data segments” transmitted, including the ST and SE segments. This quantity can be used to verify all EDI data transmitted is received by the trading partner.
The GE segment indicates the end of the data provided under a GS segment, or functional group. Multiple GS segments can be included in an EDI transmission, so this segment can indicate the end of a document type or application type.
The IEA segment is the last segment sent or received in an EDI transmission. The IEA indicates this is the end of the current transmission.
“Control Numbers” are included in all header and trailer segments as an additional means of tracking and confirming EDI transmission. Control numbers issued in the header segments must match control numbers assigned in the trailer segments. An ISA control number must match the IEA control number, the GS control number must match the GE control number, and the ST control number must match the SE control number in each EDI transmission, or there could possibly be errors. Control numbers are assigned within your EDI translation software when each EDI document is created.