Ahh... So it must be application-specific. Thanks for helping out.

>My MS Photo Editor will not recognize the file format when I try it with a bmp file renamed to photo.tch like MSWord does with renamed doc files.
>
>
>>More like I want MS Photo Editor to see an ABC extension and open the file.
>>
>>>What program do you want to associate with your jpg files that have a different file extension?
>>>
>>>
>>>>>Hi Renoir,
>>>>>
>>>>>I'm not experiencing this problem. I create a document named Tracy.Doc and then I renamed it in windows explorer as tracy.tch. Then I right clicked on the file and chose Open With... and selected MSWord. From that point on, MSWord would open the file fine.
>>>>>
>>>>>http://support.microsoft.com/default.aspx?scid=kb;en-us;307859
>>>>
>>>>Hi Tracy,
>>>>
>>>>Does it work for you with JPG files too?