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Using Expressions to Enhance Your Reports
Calculated controls use expressions as their control sources. To create a Calculated control, you must first add an Unbound control to the report. You must precede expressions with an equal sign (=); an example of a report expression is =Sum([BillableHours]). This expression, if placed in the Report Footer, totals the contents of the BillableHours control for all detail records in the report. You can build an expression by typing it directly into the control source or by using the Expression Builder, covered in Chapter 5.
