http://gdlp01.c-wss.com/gds/1/0300007351/01/eos5dmkiii-im-c-zh.pdf
(Note: Large file, in about 36MB!)
English version has not been found yet. Nevertheless, if you are interested and if you can read Chinese, go download and find out all the details by yourself.
Update (3-16): The English version of the manual can be downloaded here, via Planet 5D Blog.