The variable message of a flow contains the variables required by the Extract actions, Insert actions, and loop variables in the flow. The variable message typically also contains variables that you create for storing and working with the data processed by your flow.
You can create and modify variables at any time by opening the variable message file with the message definition editor. You can also have the host editor create variables for you during flow recording when you create an Extract action, Insert action, or recorded loop.
The variable message file contains the variable message. You can add additional messages to the variable message file if you choose. The variable message file is located in the Messages subfolder in the interface subproject of the service flow project. The name of a variable message file that is created automatically has the prefix v_.