Barcode GS1 AI coding thoughts

I'm looking for some ideas for programming techniques dealing with barcodes
that contain multiple /FNC and AI Codes.

I had a customer request serial numbers to be stripped from a barcode that
contained 3 different segments. For example.. (the parenthesis are not in
the scanned barcode. Instead that is the /FNC followed by the AI code
"93", "92", "21"). Important note, the RF Devices we use to scan these
barcodes, convert the /FNC (GS group separator) to a pipe |. This is done
because the /FNC trashed the display file screen.

(93)XXXX000000XX(92)C(91)1E1613161313

Issue one we have is with the customer. They cannot guarantee the order of
the segments. And the lengths of the elements can change. This is their
preferred format, however, said their vendors can choose to do something
different. That tends to make things difficult on us (a 3 party
warehouse).

Issue two we have is with the original developer of the process, decided to
grab the first two characters of the string. Then used hard-coded
programming to see if the string started with 93, 92, 91. Then if it did,
the program searched for the 91 segment and substringed out the serial
number.

With this being hardcoded, the customer then decided they wanted to change
91 to 21. So we had to change the program seek for 21 too.

Now, the customer is changing the 93. The 93 is now going to be 240. 3
characters instead of 2. So again here I am looking to modify the process
again.

I was thinking there has to be a better way. So I was seeking to see if
anyone else has developed a better solution.

I'm thinking of doing a translation table of some kind. I would read
through the table, then check to see if the FNC (or pipe) + AI Code exists
in the barcode. In this example, I just need what is after the 91 or 21 and
to the end of the string or to the next FNC (or Pipe).