module declaration and compilation

[SEROUL Gael]

HI, I am not sure if this is the right place, but I have a question
about the module declaration and the compilation.
The proxy module and the mod_info module are both the only modules that
have a declartion with "extern" :

extern module MODULE_VAR_EXPORT proxy_module;

All others module I have seen have a module declaration without the
"extern", like
module MODULE_VAR_EXPORT example_module;

Could someone explain the difference about these two declarations for
compilation and programs running.

Thanks


Gael Seroul