The DataTransferItemList() getter method implements support for accessing items in the DataTransferItemList using array-style syntax (that is DataTransferItemList[index]).
The SourceBuffer() getter method of the SourceBufferList interface allows the SourceBuffer objects in the list to be accessed with an array operator (i.e. [].)
The TrackDefault() getter method of the TrackDefaultList interface allows the TrackDefault objects in the list to be accessed with an array operator (i.e. [].)