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63. Tutorial for opening attachments

By Mark Alberstat

We recently received this question:

I sometimes receive attachments with my e-mails that I cannot open because I have not created a file association. Could you address this problem sometime in your column?

O. David, Dartmouth

In the Microsoft Windows environment, you can graphically see each file in your computer with a small icon. These icons are supplied by the operating system to assist you not only in navigating your system, but also organizing it. The system knows which icon to display next to each file by reading the file's extension. This is the three-letter designator at the end of the file name, preceded by a period.

The operating system knows that files that end with .doc are document files created by Microsoft Word. Unfortunately, not everything is cut-and-dried, as sometimes different programs will use the same file extension. When this happens, usually the most recently loaded program will become associated with file type.

But what happens when you have a file with an extension that the computer doesn't know or has forgotten how to recognize? You then have to reassociate the file with a program. When you have a file that has no association, there is still an icon next to the file name, but instead of looking like a familiar program icon, it is a white box with the Windows logo in the middle. This immediately tells you the computer does not know how to open this file.

To associate a file type with a program, different versions of Windows go about it in similar but slightly different ways. In general, you have to open Windows Explorer and click on the View menu item (or Tools, depending on the version of Windows). Then click on Folder Options and select File Types. You will then see a list of extensions and their related icons. It is in this interface panel that you can change or add an association.

To change an association, simply scroll through the list until you find the one you are looking for, click on it and then hit the Change button. Another window will appear, listing all the computer's loaded programs. Choose the program you think will best open this file type and then click OK.

To create a new association, click on the New button, type the three-letter extension in the appropriate box and click OK. Then find that new extension in the list and hit the Change button to find the program that will open this file type.

A problem will arise, however, when you have a file but do not have an application to open it. An example of this would be receiving a PDF document but not having Adobe's free reader. Without the proper application, associating the file with another program will not solve the problem of a file not opening correctly.

If you are unsure as to which program opens a certain file type, check at - a site that keeps track of hundreds, if not thousands, of extensions and their related programs.

Users should note that if a file does not have an extension, it cannot be associated with a program. As well, Windows will only associate one file type with one program. This means Windows cannot associate a .txt file with both Word and Notepad.

There are programs you can download, such as OpenExpert, that will allow you to associate multiple programs with a single file type. Most of these programs work by right-clicking on the file and going to the Open With menu. It is in this context menu that you will see the applications properly associated with this type of file.

The Mousepad runs every two weeks. It's a service of Chebucto Community Net, a community-owned Internet provider. If you have a question about computing, email If we use your question in a column, we'll send you a free mousepad.


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Originally published 3 July 2005


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