Adding Extensions to Open Dialog In Excel

I want to add a new File Extension to Excel so the user will have the option to open a file from a fresh Excel App Startup.

Is this possible?

Our company produce mainly TXT and CSV data files which are fine if you don't have leading zeros, but some poor soul has to open these files in Excel, format all the columns and check the data.

I want to be able to open a copy of the file called CST (Comma Separated TEXT) which won't ask to format columns, but just open them as text columns.

Any ideas or help out there?

Many Thanks

You set this up via Windows Explorer View/Options/File Types
(set the new new file type to be opened by Excel)

So you are saying that I can just add it through Explorer and it will appear in the Open Dialog Box complete with filter and a description?

So when the user selects the extension CST, I'll be able to handle that in code?

Fantastic!

I look forward to seeing an example of the Excel part?