A. You can use Windows Explorer to view file types and modify file associations. To view the list of file types, open Windows Explorer; select Tools, Folder Options; then click the File Types tab. If you don't want Windows Explorer to display a certain file type (e.g., .txt), you need to modify the file-type's attributes in the registry. You can determine a file extension's file-type name by typing

assoc .<extension></extension>

at the command prompt. For example, to determine the file-type name for the .txt extension, type

assoc .txt

and the computer will display

.txt=txtfile

To remove a file type from the Windows Explorer File Type dialog box, perform the following steps:

  1. Start a registry editor (e.g., regedit.exe).
  2. Navigate to the HKEY_CLASSES_ROOT\ registry subkey.
  3. If a binary value doesn't exist, from the Edit menu select New, Binary Value; if a value of another data type (e.g., REG DWORD) exists, delete the existing value, then from the Edit menu select New, Binary Value.
  4. Enter the name EditFlags, then press Enter.
  5. Double-click the value, set it to 01 00 00 00, then click OK.
    Click here to view image

The change takes effect immediately, and Windows Explorer will no longer display the file type. To make the file type reappear so that the user can once again change it, either delete the EditFlags value or set it to 00 00 00 00.