The Expression Editor appears when you click the "..." button for the Condition property of a formatting rule or for the Expression property of a calculated field. This dialog helps with entering a valid expression.

There are several sections in this dialog:

• The large edit box at the top is where you enter the expression.

• The list of symbols across the dialog acts as a toolbar; click a button to insert that symbol into the current cursor position in the expression. The three buttons at the right are for And, Or, and Not.

• The list of types at the lower left allows you to choose what displays in the lower middle list. Functions displays a list of the built-in functions. Note that these functions are different than the ones listed in the Expressions and Function Reference topic; the functions in that topic are used in Report Writer formulas while these ones are used in advanced layout report expressions. Operators shows the various operators you can use, such as + and -. Fields displays the fields in the result set for the report. Constants lists certain constant values, such as True and False. Parameters lists the parameters defined in the report.

• The list in the lower middle displays the type of items selected in the previous list. Choosing one of the items displays information about it in the box at the right. Double-click the item to add it to the current cursor position in the expression.

• When Functions is selected, a drop-down list appears above the lower middle list allowing you to filter the functions list by type of function.

After entering the desired expression, click OK to save it.