According to the manual :
http://orgmode.org/manual/Special-symbols.html , M-tab would perform auto complete in org mode for special symbols. However, it looks like that the key is shadowed by flyspell-auto-correct-word on my emacs and I need to rebind the key. I digged into the org.el file but failed to locate the code for key binding. Any pointer or hints are appreciated. In particular, what command is M-tab supposed to be bound to for auto completion for the special symbols? Thanks.