The old_TRK_FILE_TRACKING_INFORMATION structure is unused, but is included in this protocol because it affects the definition of the TRKSVR_MESSAGE_UNION, as defined in section 2.2.13.

 typedef struct {
   WCHAR tszFilePath[257];
   CDomainRelativeObjId droidBirth;
   CDomainRelativeObjId droidLast;
   HRESULT hr;
 } old_TRK_FILE_TRACKING_INFORMATION;