What does these void* data[] mean?

I find in the c Interfaces of clang, there is :

struct CXType
{
num CXTypeKind kind
void * data [2];
}

and in

struct CXCursor
enum CXCursorKind kind
void * data [3]
}

what does these data[2] and data[3] mean please?

In the meantime, can anyone show me how to use these C interfaces?