In order to understand the process of EDI communication more thoroughly we refer to below listed terms that describe particular elements of EDI transaction.
Segment: Segments are what make up an EDI document. Segments consist of data elements that are logically related. The following is an example of the first segment of the purchase order:
Segment Terminator: These are the special characters appearing at the end of a segment to indicate the termination of the segment (e.g., N/L). Sometimes, you can not see them, for example, the carriage return line feed like in the example above is not visible to the human eye, but it does exist. Sometimes they are visible and may look like this:
The ST and BEG segments are separated by the tilde character ~. It is important that this segment terminator does not repeat anywhere in the actual data. This can confuse the translator and cause a translation error.
Data Element: The data element is the smallest item in the EDI data. It is similar to a field in a database. The elements contain the actual data. They consist of qualifiers and values.
To illustrate this, the segments above are bold and the data elements are italic.
Element Delimiter: The data element delimiter is a special character that separates the data elements.
In this case the element delimiter is an asterisk character.
Qualifier: A qualifier is sometimes used to indicate what the values in the data elements are. In the following example DTM-01 = 106 which means “Required By”. The shipment would need to be received by 11/03/2005.
In the following example DTM-01 = 063 which means “Do Not Deliver After”. The shipment would be late after 11/03/2005.
There are more than 100 qualifiers available in the EDI standards just for the date and time segments. Using qualifiers eliminates the need to have dedicated fields. For example, BEG-03 is the purchase order number. It does not need a qualifier. In the case of date types, with more than 100 possibilities, it would be inefficient and cumbersome to allot a dedicated field to each one.
Composite Data Elements: Are a set of sub-elements that represent a single named item. Thinking of them as a set of child elements of a regular data element can be helpful. For example the REF segment three regular elements and one composite element:
REF01 – Ref ID qualifier (element ID 128)
REF02 – Ref ID (element ID 127)
REF03 – Description (element ID 352)
REF04 – Ref ID (element ID C040)
The regular element separator separates REF01, REF02, REF03 and REF04, and the sub-element separator separates the sub-elements in REF04. If the element separator is “*”, the sub-element separator is “>” (according to ISA-16), and segment the Terminator is “~”, the REF segment can look like this:
Loops: Loops are used to combine similar segments together; usually loops contain a parent-child relationship. For example, the N1 segment loops here twice. The first portion contains the Vendor’s address information with child segments of N3 and N4 that contain the vendors address. The second portion contains the Ship To Store address with child segments of N3 and N4 that contain the vendors address.
N1*VN*DOG FOOD COMPANY*ZZ*02633
N3*545 STREET AVE
N1*ST*PETCO GREEN BAY*92*1903
N3*2390 E. MASON ST