Creating and Registering a New File Type

If you want, you can create a file of an unregistered file type simply by specifying an extension that hasn’t been used. You won’t normally need to do this, because any program you install on Windows should automatically register its own file types. But you may sometimes need to use this technique for a program that was designed for an earlier version of Windows and that can’t install itself successfully on Windows Vista. You may be able to get the program running by copying an existing installation across to your Windows Vista computer - but that probably won’t include details of the file types.

To create and register a new file type, open Notepad, enter a space, and save the

new document it automatically creates under a name that uses the extension you want - for example, “Example.888” if you need to use the 888 extension. You must enter the filename and extension within double quotation marks, because otherwise Notepad automatically assigns the .txt extension, which is associated with the TXT file type. Exit Notepad once you’ve created the file.

Now open an Explorer window to the folder in which you created the file, change to Details view, and you’ll see the .888 extension or whatever extension you chose displayed. Explorer decides that the file type for this file is “888 File”; you’ve created a new file type.

Now you need to tell Windows which program to use for opening this file type.

1. Double-click the file in Explorer. Wait while Windows consults the Registry about the file type and comes up dry. Windows then displays the Windows Cannot Open This File dialog box.

2. Choose the Select a Program from a List of Installed Programs option button. Windows displays a slightly different version of the Open With dialog box, as shown here.

3. In the Type a Description That You Want to Use for This Kind of File text box, enter the name you want to assign to the file type. Make it as concise and descriptive as possible.

4. In the Programs list box, select the program you want to associate with the file type. If the program isn’t listed, click the Browse button and use the resulting Open With dialog box to identify it.

5. Select the Always Use the Selected Program to Open This Kind of File check box.

6. Click the OK button. Windows creates the file type, creates Registry entries for it, and opens the file in the specified program. Now, when you double-click a file of your new file type, Windows opens the file using the program you chose.