How to save a Revit (2008) file into an older version (9.1)?

[cku]

I have Revit 9.1 and Revit Architecture 2008 in the office. Some most of the users have 9.1 while few users have 2008.
A user, who has 9.1, needs a file created in 2008, but the user can't open the file because of compatibility.
Is there an easy to save into 9.1 format from 2008?
I am not a Revit user, so I have no idea about it. I tried Save As, but there wasn't an option to save into an older format unlike AutoCAD.
The reason was there was an error message saying that there was a corrupt element in the file, but the recovery failed it. So he asked another user, who has Revit Architecture 2008., to recover and save into 9.2 format.
Revit Architecture 2008 is able to recover the file, but I can't find an option to save into an older version.
I believe there must be a way to save into older version.
Is there as way to recover the file without opening the file like AutoCAD?
Please recommend the best way to recover a file when there is a corrupt element in the file.
Please help me.
Any comments will be appreciated.

By the way, anyone knows why Autodesk didn't make file format to compatible with an older version?

[gbrowne]

The reason it's not compatible is because the software invariably will have new features in it which don't exist in the older versions.

I would contact the factory and I would imagine they will be able to help you out, for both the corrupt file and perhaps backdating to older versions.

[clog boy]

As far as I know it's not possible to save for an older version. This has two reasons I can think off. One is pure marketing, the other is you can't create backward compatibility for future functions.

[dhurtubise]

How about stability issue. I really hope no one will fall for that backward compatibility.
3ds max is not and the users doesn't complain.

[Jay Zallan]

There is no way to save to older versions, as you've probably read. Are your teams using the most current build of RAC 2008 (http://cad-vs-bim.blogspot.com/2007/06/keep-up-with-most-current-revit-builds.html) and attempted a 'recover' using that current version?

[dgreen.49364]

http://forums.augi.com/showthread.php?t=60223&highlight=saving