Gets a value indicating whether the page is involved in a cross-page postback.
Assembly: System.Web (in System.Web.dll)
ASP.NET provides two mechanisms for transferring control from one page to another. You can use the Transfer method to transfer processing between pages, or you can make a cross-page request by assigning a page URL to the PostBackUrl property of a button control that implements the IButtonControl interface.
In either case, the PreviousPage page property will contain an object that represents the previous or originator page. If, for example, Page A posts to Page B, Page A's property (accessible through the PreviousPage property) will be true and Page B's PreviousPage property will have the name of Page A.
Available since 2.0