You can use the Expression shape to enter any expression you choose in your orchestration. For example, you can make a .NET-based call to run an external program, or manipulate the values of your orchestration variables. It is generally not good practice to use it to perform high-level orchestration logic, which preferably would be visible in the orchestration drawing itself. Your orchestration is easier to understand and maintain if your Expression shapes contain simple and modular expressions.
To do this
Specify the expression you want to use.
Report to Analyst property
Select True if you want to make this shape viewable in the Visual Business Analyst Tool.