Called during ViewState operations to determine an index value that represents the type of a CollectionObject. Used only in situations where a collection can contain multipe types within it, where all the types still derive from CollectionObject. In the default case where there is only one type in the collection, the base implementation returns 0.
Target Platforms: Windows 10, Windows 8.1, Windows 8, Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2
