Tracy, put some additional stars to Sergey (get him the Milky way). Since yesterday I've fought with that!

>Yes you are correct. It turns out that device class guids are stored in devguid.h and device interface guids are stored in ntddkbd.h
>
>
>
>>Isn't the first one a device guid and the second one device INTERFACE guid?
>>
>>>Any idea what is the difference between lc_HidGuid and ls_HIdGuid in the below code? They are not the same values, but I cannot figure out why...
>>>

>>>#DEFINE GUID_Size  16
>>>lc_HidGuid = SPACE( GUID_Size )
>>>ls_HidGuid = SPACE( GUID_Size )
>>>
>>>*The GUID_DEVCLASS_HIDCLASS guid below is taken from devguid.h
>>>*GUID_DEVCLASS_HIDCLASS, 0x745A17A0, 0x74D3, 0x11D0, 0xB6, 0xFE, 0x00, 0xA0, 0xC9, 0x0F, 0x57, 0xDA
>>>#DEFINE GUID_DEVCLASS_HIDCLASS ;
>>>	CHR(0xA0) + CHR(0x17) + CHR(0x5A) + CHR(0x74) + ;
>>>	CHR(0xD3) + CHR(0x74) + CHR(0xD0) + CHR(0x11) + ;
>>>	CHR(0xB6) + CHR(0xFE) + CHR(0x00) + CHR(0xA0) + ;
>>>	CHR(0xC9) + CHR(0x0F) + CHR(0x57) + CHR(0xDA)
>>>lc_hidGuid = GUID_DEVCLASS_HIDCLASS             && <--------------Check lc_hidGuid Value here
>>>
>>>DECLARE HidD_GetHidGuid IN HID ;
>>>     STRING @ O_sHidGuid
>>>HidD_GetHidGuid( @ls_HidGuid )                  && <--------------Check ls_HidGuid Value here
>>>

>>>Now compare the values of lc_hidGuid and ls_hidGuid, shouldn't they be the same?
>>>
>>>
>>>http://msdn.microsoft.com/library/default.asp?url=/library/en-us/Hid_r/hh/HID_r/hidfunc_61242b6f-b794-48c7-84b8-ef8d0d4e69af.xml.asp
>>>
>>>HidD_GetHidGuid
>>>The HidD_GetHidGuid routine returns the device interface GUID for HIDClass devices.
>>>
>>>VOID
>>> HidD_GetHidGuid(
>>> OUT LPGUID HidGuid
>>> );
>>>
>>>
>>>Parameters
>>>
>>>HidGuid
>>>Pointer to a caller-allocated GUID buffer that the routine uses to return the device interface GUID for HIDClass devices.
>>>
>>>Return Value
>>>None.
>>>
>>>Headers
>>>Declared in hidsdi.h. Include hidsdi.h.
>>>
>>>Comments
>>>Only user-mode applications can call HidD_GetHidGuid.