[Help] Reason on when to declare and protect ZEND_API function

Hello internals, I am trying to read Zend header files to understand its functional interfaces, but have got confusion and anybody knows why zend_startup_system_id() and zend_finalize_system_id() do not have to be protected by BEGIN_EXTERN_C()/END_EXTERN_C() enclosure, but zend_add_system_entropy() has to. Is the following code intentional for any reason? And also, these two functions do not have ZEND_API attribute. Thanks. Zend/zend_system_id.h BEGIN_EXTERN_C() /* True global; Write-only during MINIT/startup */ extern ZEND_API char zend_system_id[32]; ZEND_API ZEND_RESULT_CODE zend_add_system_entropy(const char *module_name, const char *hook_name, const void *data, size_t size); END_EXTERN_C() void zend_startup_system_id(void); void zend_finalize_system_id(void); ======================================= Tony Su (Su, Tao) make a 'lazy' programmer diligently with efficiency