Interchange Syntax Extension

New envelope ISX – Interchange Syntax Extension. Great for escape characters!

There is a major enhancement coming to X12 in version 8010. 

There is a new optional segment ISX – Interchange Syntax Extension. This segment goes just below the ISA segment. This new segment has three features:

  1. Allows for an (release) escape character data conflict due to do delimiters. ISX-01
  2. Allows for a language to be indicated that will be used in the rest of the data through character encoding. ISX-02.
  3. Allows for future code sets and qualifiers to be used in the data. For example, the transaction version in GS08 can be 4010 but you may be able to use qualifiers with the ISX-03 data element and you can even indicate the subrelease through ISX-04 (e.g. VICS, UCS, X231).

Here is the official definition of the segment according to the X12 standards committee:

“To allow the interchange sender to specify additional information required for the interchange receiver to perform syntax interpretation of the interchange. This segment allows specification of a release character, character encoding, and similar capabilities. An Interchange Syntax Extension segment is used by the interchange sender to indicate to the interchange receiver additional information required for the correct syntactic processing of the interchange. An Interchange Service Extension is optional and only used by mutual agreement between the interchange sender and interchange receiver.”

This segment contains 4 data elements:

ISX-01 Release Character 

The release character prevents the character immediately following its appearance from being treated as a delimiter or a segment terminator. For example, let’s say the asterisk character is part of the company name STAR*ALLIANCE. The N1 segment with the name in N102 may look like this: 


Prior to version 8010 and without the ISX segment the EDI translator would try to parse the segment as N1-01 as ‘ST’, N1-02 as ‘START’ and N103 as ‘ALLIANCE’. Either the sender would have to get rid asterisk from the logo in the EDI file or if they kept it, this would cause a translation error.

In 8010 if we use the ISX-01 to indicate a release character of ? then we can send the N1 segment as:


The value in N102 will now be parsed as “STAR*ALLIANCE” thanks to the escape character.

A release character can apply to an x12 data element delimiter, a segment terminator, or even the release character itself.

If a release character appears in the data and it is not followed by a syntax item, the release character is ignored. For example: N1*ST*STAR?ALLIANCE the value in N1-03 would be interpreted as “STAR?ALIANCE”. The HCL Software company has a good article on the definition of release characters.

ISX-02 Character Encoding

X12 Definition: “XS-02 Identifies a scheme for representing a set of graphical characters with bit patterns.”

This allows for international characters (e.g. Cyrillic characters) to be used in the data. 

For example, qualifier “6” = ISO 8859-5 which is the character encoding for Cyrillic letters. Another example is qualifier “10” for ISO 8859-6 which is the character encoding for 

ISX-03 Overriding X12 Version / Release / Subrelease Code

X12 Definition: “This code indicates the version, release, and subrelease of the value as agreed to by trading partners to override what is in the first six characters in GS08. Used only when code in GS07 is X.”

Let’s say you are on version 5010, but you need a new qualifier from version 7030 INS08 Employment Status Code data element IA Inactive. IA is not a qualifier available in 5010. You can override the GS08 5010 version (only for qualifiers and not other attributes like min/max length) in position ISX-03 7030.

ISX-04 Industry Identifier

X12 Definition: “An industry or trading partner identifier for an implementation guide. This is the type of content as characters 7 through 12 of GS08. For example, VICS or X231.”

In position ISX-03 you can overwrite the version number and in this position you can override the implantation guide identifier. If ISX-04 is used then ISX-04 is required.

ISX Full Examples

ISX*? Escape character is ?

ISX*?*10 Escape character is ? and character encoding is 10 which is ISO 8859-6 – Arabic.

ISX*?*6*7030 Escape character is ? and character encoding is ISO 8859-5 which is Cyrillic.

ISX*?*6*7030*VICS Escape character is ? and character encoding is ISO 8859-5 which is Cyrillic AND implementation guide is VICS.

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