ToggleItem Element (RDL)
Specifies the text box that users click to show or hide the current item.
When a user clicks the text box specified in the ToggleItem element, the parent of the Visibility element ("current item") is alternately shown or hidden. If ToggleItem is not specified, the current item does not toggle.
The value of ToggleItem must be a text box in the same grouping scope as the current item, or in any containing grouping scope. It can be a text box within the current item only if the current grouping scope contains a value for the Parent element.
ToggleItem cannot be used in a page header or footer, nor can it refer to items within them.