MouseHookDLL 未定义的标识符

Question

各位大侠帮忙啊
网上拷贝的dll代码 
下面代码中 MouseHookDLL 到底是怎么回事，一定要是Dll 的名称吗？extern "C" int APIENTRY
DllMain(HINSTANCE hInstance,DWORD dwReason, LPVOID lpReserved)
{
UNREFERENCED_PARAMETER(lpReserved);
if(dwReason == DLL_PROCESS_ATTACH)
{
if(!AfxInitExtensionModule(MouseHookDLL, hInstance))
return 0;
new CDynLinkLibrary(MouseHookDLL);
glhInstance = hInstance;//插入保存DLL实例句柄 
}
else if(dwReason == DLL_PROCESS_DETACH)
{
AfxTermExtensionModule(MouseHookDLL);
}
return 1;// ok 
}