A parameter is a value that filters the data displayed in your report. For example, if you have a sales report that lists each sales group and each sales rep within that group and you want to see one particular sales group at a time, you would use the Sales Group field as the parameter. Parameters are defined wherever report data sources and data sets are defined.
The View Parameters dialog will automatically load any default values and display any available value sets that are predefined in the report.
In the event of cascading parameters, or parameters that depend on other parameters, the View Parameters dialog will leave the first dependent parameter blank and disable the rest of the cascading parameters. In the example below, Category is an independent parameter. The Subcategory value depends on Category and the Product value depends on Subcategory. Initially, Subcategory is enabled, but Product is disabled.
Once a value has been selected for a parameter, the immediate subsequent dependent parameters will be enabled.
In this example, once a value for Subcategory has been selected, the Product field becomes enabled. If there were any parameters that depended on Product, they would remain disabled.
Once a value for Product is selected, any parameters that were immediately dependent on Product would be enabled. However, in this example, there are no additional parameters.
If a parameter value is changed, any dependent parameters will be reset. This means the first dependent parameter will be cleared. All other cascading parameters that depend on the changed value will be disabled.