Patch 5.2.0d Edit
Patch 5.2.0d is the unofficial name for the patch build 16701 that came out two days after the unofficiallt named "Patch 5.2.0c" build 16685. There is almost no info on this patch build and there has been no official acknowledgement of the release of this patch build. This client could correspond to the March 14, 2013 slate of hotfixes. It isn't clear why a client patch is needed.
See also Edit