import of iBase.h

Hello,

	I have a technical question which relates to the API Guide :
it explains that "ibase.h", is the header file which should be
included 
in all source code modules for API applications. Ibase.h contains API
function prototypes. It also contains structure, typedef, parameter 
definitions, and macros required by various API functions.

	When I read ibase.h, I'm surprised to see that there is no code which 
specializes for export like :
extern "C"  __declspec(dllexport)  isc_commit_retaining ... / ...

How is does it works ?
Thanks for your answer(s).