Set the value of a variable
Variable Name: Give the name of the variable you want to set. The variable's value can be accessed later with the Expression: [[var:name]] where name is the variable actual name.
Value: The value you want to store in the variable. That value can be of any type, including expression or data source values. You can apply Formatters on values
Data Source: If a Data Source is selected, the variable will bet associated with the current record of that data source. Variables associated with data sources are accessed using the "dsvar:" expander.Tutorial on dsvar expander