Script
You can use the script step to perform any modification of
incoming message content or headers.
How to create a script see Creating scripts.
A data flow cannot be activated if it uses a script that has no approved version available. Activated data flows use the latest approved version available of the script. When the script is updated with a new approved version, the data flows do not require re-activation. They start using the newly approved version of the script when their last run with the older version completes.