A CLSID is a globally unique identifier that identifies a COM class object. If your server or container allows linking to its embedded objects, you need to register a CLSID for each supported class of objects.

Registry Key


Registry key Description
AppID Associates an AppID with a CLSID.
AutoConvertTo Specifies the automatic conversion of a given class of objects to a new class of objects.
AutoTreatAs Automatically sets the CLSID for the TreatAs key to the specified value.
AuxUserType Specifies an application's short display name and application names.
Control Identifies an object as an ActiveX Control.
Conversion Used by the Convert dialog box to determine the formats an application can read and write.
DataFormats Specifies the default and main data formats supported by an application.
DefaultIcon Provides default icon information for iconic presentations of objects.
InprocHandler Specifies whether an application uses a custom handler.
InprocHandler32 Specifies whether an application uses a custom handler.
InprocServer Specifies the path to the in-process server DLL.
InprocServer32 Registers a 32-bit in-process server and specifies the threading model of the apartment the server can run in.
Insertable Indicates that objects of this class should appear in the Insert Object dialog box list box when used by COM container applications.
Interface An optional entry that specifies all interface IDs (IIDs) supported by the associated class.
LocalServer Specifies the full path to a 16-bit local server application.
LocalServer32 Specifies the full path to a 32-bit local server application.
MiscStatus Specifies how to create and display an object.
ProgID Associates a ProgID with a CLSID.
ToolBoxBitmap32 Identifies the module name and resource ID for a 16 x 16 bitmap to use for the face of a toolbar or toolbox button.
TreatAs Specifies the CLSID of a class that can emulate the current class.
Verb Specifies the verbs to be registered for an application.
Version Specifies the version number of the control.
VersionIndependentProgID Associates a ProgID with a CLSID. This value is used to determine the latest version of an object application.



The HKEY_LOCAL_MACHINE\SOFTWARE\Classes key corresponds to the HKEY_CLASSES_ROOT key, which was retained for compatibility with earlier versions of COM.

The CLSID key contains information used by the default COM handler to return information about a class when it is in the running state.

To obtain a CLSID for your application, you can use the Uuidgen.exe, or use the CoCreateGuid function.

The CLSID is a 128-bit number, in hex, within a pair of curly braces.