Map Group Properties Dialog Box, Variables
Select Variables to add custom group variables to a map layer. A group variable is evaluated when the first group instance is processed and can only be referenced from an expression in the current scope or a child scope. Because the variable is calculated once per group instance, each reference to the variable always uses the same value. Click the Expression (fx) button to edit an expression that sets the value of the option.
Select this option to add a variable to the list.
Select this option to delete the selected variable from the list.
Type a case-sensitive name that begins with a letter and has no spaces. The name can include letters, numbers, or underscores (_) and must be unique in the report.
Type a value for the variable.
To include a reference to a variable from an expression, use Visual Basic collection syntax. For example, the following expression specifies a group variable named CitySales: =Variables!CitySales.Value.