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.
The following list describes the ISA segments shown in Figure 2–5:
Authorization Information Qualifier
Security Information Qualifier
Interchange ID Qualifier
Interchange Sender ID
Interchange ID Qualifier
Interchange Receiver ID
Date
Time
Repetition Separator
Interchange Control Version Number
Interchange Control Number
Acknowledgment Requested
Usage Indicator