Registry DataBase : HKEY_CLASSES_ROOT = HKCR
System : 95, 95+IE4.x, 98, ME, NT, 2K
Alias of
HKLM\SOFTWARE\Classes which contains file extensions associations, CLSIDs file and object types. This key is dynamically recreated at each startup.
Extensions - CLSIDs - Context menu options - Windows 98/ME - Standard CLSIDs
Top Extensions
File extensions are the extensions of registered file types, that's why this series of subkeys starts with a dot except for the * key. This joker refers to any file type, registered or not. In fact, it corresponds to .* and adds an option to the context menu of any file type. You will see the following subkeys in HKCR extensions entries :
\shellex\ContextMenuHandlers   Context menu options. For instance, Winzip's options for creating an archive or for adding the selected file to an existing archive. These entries refer to a CLSID key containing the name of the DLL which supports this menu extension.
\shellex\PropertySheetHandlers   Properties dialog box tabs. These entries refer to a CLSID key containing the name of the DLL which displays the property page corresponding to each tab.
\ShellNew   File and options for creating a new file of this type from the New menu on the desktop or in folders. Here is an example.
Some file types will also display the entry Content Type which contains character strings such as application/msaccess, audio/x-midi, or video/x-mpeg. These are MIME types used to tell browsers what to do with the data, start an application, download a file, display some text or a picture, play some music or a video. These definitions are stored in the key HKCR \MIME \Database \Content Type.
CLSID means class identifier. Key names are unique identifiers called GUID for globally unique identifier, made of 32 hexadecimal digits in the following format : 8-4-4-4-12. You will see the following subkeys in HKCR\CLSID entries :
\Default   Object name
\DefaultIcon   Path for associated icon
\InprocServer   Process manager DLL
\InprocServer32   32 bit process manager DLL
\InprocHandler   Process server DLL
\InprocHandler32   32 bit process server DLL
\LocalServer   OLE local server
\LocalServer32   32 bit OLE local server
\ProgID   Class definiton
\MiscStatus   Server data
\shell   Application to execute and parameters, if any. Here is an example and a complete description of \shell's options.
\shellex   See the Extensions section
\ShellFolder   Contains the entry Attributes
\ToolboxBitmap   Toolbar parameters
\TypeLib   Type libraries
\Version   Application version number
\Implemented Categories   CLSID dynamically created at execution
\QuickView   Quickview manager (sometimes)
Top Context menu options
Key : HKCR \CLSID \{CLSID} \ShellFolder
Entry : Attributes
System : 95, 95+IE4.x, 98, ME, NT, 2K
Type :
For example :
Recycle Bin's Attributes entry : 40 01 00 20
Recycle Bin's context menu options : Properties (bit 30), Paste (bit 16), Open, Explore (bit 5)

Enables adding or removing the objects' context menu options. To combine 2 options or more below, make the sum of their values and indicate the total.
Bit   Hex   Action
30   40 00 00 00   Properties
29   20 00 00 00   Delete
28   10 00 00 00   Rename
25   02 00 00 00   Cut
24   01 00 00 00   Copy
16   00 01 00 00   Paste
5   00 00 00 20   Open, Explore (\shell subkey menus)
Also enables changing object icons :
Bit   Hex   Action
12   00 00 02 00   Adds a hand to the icon, to indicate it is shared
13   00 00 04 00   Adds a big shortcut arrow to the icon
14   00 00 08 00   Gives the icon a disabled look
Top Windows 98/ME
There are keys specific to Windows 98/ME in HKCR :
\.Desklink   Corresponds to the command Desktop Shortcut in the Send To submenu of context menus.
\.mydocs   The Properties option of the My Documents icon leads to a page called Target showing that the shorcut refers to the indicated folder, for example C:\My Documents. The Delete option is replaced with Remove from desktop. If you choose that option, the icon is deleted from the desktop and a ShellNew key is added into the .mydocs key, which displays My Documents Folder in the New menu. If you create a new My Documents icon on the desktop, the ShellNew key will be removed.
AllFileSystemObjects   Special class referring to any file system object type. By default, this class adds the Send To menu to each file or folder's context menu.


© Franck Kiechel 2000-2001