To have a user be prompted with a parameter, you must include the parameter somewhere in the report in a record or group selection, in a formula, or simply as a field on the report.
To design a parameter field
This is the text that appears in the Enter Parameter Values dialog box when the report is refreshed.
The user will be able to choose any values you move to the Default Values area. If you want to limit the selection, move only the values you would like the user to choose from.
Tip For a string parameter field that you are setting the default values for, you can choose to enter an Edit Mask in the Edit Mask field, rather than specifying a range.
The Create Parameter Field dialog box appears.
Incorporating Parameters into Formulas | Limiting Entry Type and Format in Parameters