EDI Structure description
EDI structure standards govern how EDI documents are structured, and define the rules for their use. North American companies follow the X12 standard, while other parts of the world follow the EDIFACT standard. The X12 standard is made up of hundreds of documents called EDI structure ‘Transaction Sets.’ Transaction sets are made up of ‘Data Segments’ and ‘Data Elements,’ of which there are hundreds, and thousands respectively, in the standards dictionary. By putting various combinations of data segments and data elements together in a structured format, you end up with a transaction set that has meaning.
Data Segments and Data Elements
The example of EDI structure below shows what an 850 purchase order looks like. Each line is called a Data Segment (1) and begins with the Segment Name (2). For example, ‘N1’ represents name and address line 1 while ‘PO1’ represents purchase order line 1. Following the Segment Name is a number of Data Elements (3). In the N1 segment, the code ‘BT’ means it’s a bill-to name and address. Data elements are separated by a single character, usually an asterisk (*) (4). A segment ends with a single character— in this example a tilde (~) (5).
Other EDI documents such as an 835 Health Care Claim will have their own sets of data segments and data elements. Segments such as the N1 overlap many transaction sets, but an 835 will have its own segments and elements that are unique to healthcare. Any number of data segments come together to form a transaction set. In this example there are 32, as shown in the control counter stored in the very last segment (SE). You will notice that the PO1, PID and PO4 segments repeat multiple times, just as they would on a paper-based purchase order. There is flexibility in how an industry or company uses the EDI standards. For example, a purchase order going from a retailer to its supplier will look very different from a purchase order going from a mining company to its supplier. The drawback is when one supplier receives purchase orders from five different customers, and they each structure their 850s differently. The supplier is burdened with the task of handling the five different 850 layouts.