Interchange Envelopes (ISA/IEA)

The Interchange Envelope, often referred to as the “outer envelope,” is the wrapper for all the data to be sent in one transmission. It can contain multiple Functional Groups. This characteristic means that transactions of different types can be included in the Interchange Envelope, with each type of transaction stored in a separate Functional Group.

The Interchange Envelope is defined by the header and trailer; the Interchange Control Header (designated ISA) appears at the beginning, and the Interchange Control Trailer (designated IEA) appears at the end.

As well as enveloping one or more Functional Groups, the ISA and IEA segments include:

• Data element separators and data segment terminator

• Identification of sender and receiver

• Control information (used to verify message was correctly received)

• Authorization and security information, if applicable

The sequence of information transmitted is:

• ISA

• Optional interchange-related control segments

• Actual message information, grouped by transaction type into Functional Groups

• IEA

See Figure 2–5 and Figure 2–6.

Figure 2–5 Example of an Interchange Header (ISA)

The following list describes the ISA segments shown in Figure 2–5:

1. Authorization Information Qualifier

2. Security Information Qualifier

3. Interchange ID Qualifier

4. Interchange Sender ID

5. Interchange ID Qualifier

6. Interchange Receiver ID

7. Date

8. Time

9. Repetition Separator

10. Interchange Control Version Number

11. Interchange Control Number

12. Acknowledgment Requested

13. Usage Indicator

Figure 2–6 Example of an Interchange Trailer (IEA)