Dr. Dos;
Did you click the (BLUE) Related Topics at the bottom of the Help article you
mentioned?
From XP Help:
===================
[To modify an existing file type
Open Folder Options in Control Panel.
Click Start, point to Settings, and then click Control Panel.
Double-click Folder Options.
On the File Types tab, click the file type you want to change, and then click
Advanced.
If necessary, modify the file type description, and click Change Icon to change
the file type icon.
Under Actions, click the command you want to modify, and then click Edit,
Remove, or Set Default. Click New to add a new command to the Actions list.
Notes
After you specify a new action, the corresponding command appears on the menu
when you right-click a file with the associated extension.
In the New Action dialog box, you can click Browse to find the program you want
to specify for the action.
All files that have the file name extension will use the icon and commands you
specify.]
===================
[To associate a file name extension with a file type
Open Folder Options in Control Panel.
Click Start, point to Settings, and then click Control Panel.
Double-click Folder Options.
On the File Types tab, click New.
Type a new or existing file name extension, and then click Advanced.
In Associated File Type,
Type or select New to create a file type to associate with the file name
extension.
-or-
Type or select a different file type to associate with the extension.
Notes
When you type a file extension in the Create New Extension dialog box, the
Associated File Type list displays the file type that is associated with that
extension. To select New, scroll to the top of the list.
For information about how to make modifications to the file type, click Related
Topics.
To change the program that opens a file, on the File Types tab, under
Registered file types, click the file type, and then click Change.]