How to: Build a Variable Expression
In the Expression Builder, you can build an expression that contains the name of a variable.
To build a variable expression
When available, click the ellipsis (...) button to open the Expression Builder.
Perform one of the following:
In the main expression box, type a variable name.
In the Variables list of the builder, select a system variable name.
Click OK.
For more information, see Expression Builder Dialog Box.