ActiveX .idl与.odl的区别

.odl和.idl在com中的功能相同. 
前者是ActiveX中的 后者是ATL中. 

可在前者的文件中 用 #import "XXXXX.idl" 的方式包含后者. 反过来没有试过. 
2.
When using IDL, you must declare the interfaces that will generate the C++ source files outside of the library declaration. For the ODL, this step is not necessary. Other than a few minor language differences, the IDL and ODL are identical in terms of syntax and organization. 
3.
ODL是Microsoft对IDL的扩展
4.
odl ---对象描述语言 
idl ---接口描述语言 
其实是一个功能就是在写法上有些不同，eg: 
odl: 
[ 
uuid(3C591B20-1F13-101B-B826-00DD01103DE1), // LIBID_Lines. 
helpstring("Lines 1.0 Type Library"), 
lcid(0x09), 
version(1.0) 
] 
library Lines 
{ 
importlib("stdole.tlb"); 

[ 
uuid(3C591B25-1F13-101B-B826-00DD01103DE1), // IID_Ipoint. 
helpstring("Point object."), 
oleautomation, 
dual 
] 
interface IPoint : IDispatch 
{ 
[propget, helpstring("Returns and sets x coordinate.")] 
HRESULT x([out, retval] int* retval); 
[propput, helpstring("Returns and sets x coordinate.")] 
HRESULT x([in] int Value); 

[propget, helpstring("Returns and sets y coordinate.")] 
HRESULT y([out, retval] int* retval); 
[propput, helpstring("Returns and sets y coordinate.")] 
HRESULT y([in] int Value); 
} 
[ 
uuid(3C591B21-1F13-101B-B826-00DD01103DE1), // CLSID_Lines. 
helpstring("Lines Class"), 
appobject 
] 
coclass Lines 
{ 
[default] interface IPoint; 
interface IDispatch; 
} 
} 
idl： 

[ 
uuid(3C591B25-1F13-101B-B826-00DD01103DE1), // IID_Ipoint. 
helpstring("Point object."), 
oleautomation, 
dual 
] 
interface IPoint : IDispatch 
{ 
[propget, helpstring("Returns and sets x coordinate.")] 
HRESULT x([out, retval] int* retval); 
[propput, helpstring("Returns and sets x coordinate.")] 
HRESULT x([in] int Value); 

[propget, helpstring("Returns and sets y coordinate.")] 
HRESULT y([out, retval] int* retval); 
[propput, helpstring("Returns and sets y coordinate.")] 
HRESULT y([in] int Value); 
} 
[ 
uuid(3C591B20-1F13-101B-B826-00DD01103DE1), // LIBID_Lines. 
helpstring("Lines 1.0 Type Library"), 
lcid(0x09), 
version(1.0) 
] 
library Lines 
{ 
importlib("stdole32.tlb"); 
importlib("stdole2.tlb"); 

[ 
uuid(3C591B21-1F13-101B-B826-00DD01103DE1), // CLSID_Lines. 
helpstring("Lines Class"), 
appobject 
] 
coclass Lines 
{ 
[default] interface IPoint; 
interface IDispatch; 
} 
}