What is the ISA header? - Understanding EDI 

 
In this post, we will breakdown each of the components of an ISA header for EDI X12. 

The ISA (Interchange Control Header) is a crucial component that appears at the beginning of every EDI X12 transmission. It contains vital information about the sender, receiver, and control elements that ensure proper routing and processing of the EDI data. Let's examine each field in detail to understand its significance in electronic data interchange. 

Here’s an example ISA Segment: 

ISA*00*          *00*          *ZZ*SENDERID*ZZ*RECEIVERID*20240116*1250*U*00401*000000001*0*P*:*~
...
IEA*1*000000001~

• ISA-01 (Authorization Information Qualifier): This is a two-character field that indicates the type of authorization information used in ISA-02. The most common value is "00", which means no authorization information is present, and ISA-02 will contain spaces. Other values like "03" indicate different types of authorization information may be present. 
• ISA-02 (Authorization Information): This is a ten-character field that contains the authorization information. When ISA-01 is "00", this field should contain 10 spaces. If ISA-01 specifies a different authorization type, this field would contain the actual authorization information padded with spaces to reach exactly 10 characters. 
• ISA-03 (Security Information Qualifier): This is a two-character field that specifies the type of security information used in ISA-04. Similar to ISA-01, the most common value is "00", indicating no security information is present, and ISA-04 will contain spaces. 
• ISA-04 (Security Information): A 10-character field that contains security information. When ISA-03 is "00", this contains 10 spaces. 
• ISA-05 and ISA-07 (Interchange ID Qualifiers): Two-character codes identifying the format of the sender and receiver IDs. Common value is "ZZ" for mutually defined identifiers. 
• ISA-06 and ISA-08 (Interchange Sender/Receiver ID): 15-character fields containing the sender and receiver identifications. 
• ISA-09 (Interchange Date): Six digits representing the date (YYMMDD). 
• ISA-10 (Interchange Time): Four digits representing the time (HHMM). 
• ISA-11 (Interchange Control Standards): Single character indicating the standards used. Usually "U" for U.S. EDI standards. 
• ISA-12 (Interchange Control Version): Five characters indicating the version of the ISA segment (e.g., "00401"). 
• ISA-13 (Interchange Control Number): Nine-digit number uniquely identifying the transmission. 
• ISA-14 (Acknowledgment Requested): Single digit indicating if an acknowledgment is required (0=no, 1=yes). 
• ISA-15 (Usage Indicator): Single character indicating test ("T") or production ("P") data. 
• ISA-16 (Component Element Separator): Single character used to separate component data elements. 
  

 
Understanding the ISA header is crucial for anyone working with EDI X12 transmissions. Each field serves a specific purpose in ensuring secure, accurate, and traceable data exchange between trading partners. While the format may seem complex at first, its structured nature helps maintain consistency and reliability in electronic business communications. Remember to always validate your ISA headers carefully, as errors in this segment can cause entire transmissions to fail. 

Hendricks does a great job at capture each unique requirement into a standard app on our app store. We help teams get connect between platforms like Shopify, WooCommerce, Big Commerce, Adobe Commerce and EDI. We work with your EDI partners on your behalf to save you the effort of having to become an EDI expert. Think of Hendricks as the “Google Translate between EDI and E-Commerce platforms”. 

If you have any questions, feel free to reach out to hello@hendricks.so.