org-tab-before-tab-emulation-hook is a variable defined in `org.el'.
Its value is
nil
This variable may be risky if used as a file-local variable.
Documentation:
Hook for functions to attach themselves to TAB.
See `org-ctrl-c-ctrl-c-hook' for more information.
This hook runs after every other options for TAB have been exhausted, but
before indentation and insertion takes place.