Each time you save changes, a new version of the file is created in your workspace, and the previous version is moved to the OldVersions\ folder. Other designers who are referencing the file continue to see the earlier version of the file and do not see the new version until you check the file back in to the workgroup location in semi-isolated projects, or save the file in shared projects, and they refresh their view of the assembly.
What happens when you save a file?
Several actions happen automatically when you save a file.
Every save writes a new globally unique version ID to the file to identify it. Each Autodesk Inventor session remembers which version ID it is accessing. If you try to reopen the file at the normal location but the version ID has changed, Autodesk Inventor assumes someone else saved or checked it in, so the appropriate version of the file is opened from the OldVersions\ folder. The version of the file that is opened is used from that point forward to access additional information. Note the old version of the file is restored, but not the state of an assembly.
How do projects control file versions?
In a project, an option controls the number of versions saved in the OldVersions folders. In the lower pane of the project editor, click to expand Options. Click Old Versions To Keep On Save, and then right-click and select Edit from the pop-up context menu. Now enter a value in the field and press Enter to set the number of versions to keep.
After you save a file, other designers who reference the file continue to see the old version of the file until you check in the file to the workgroup.
If you work in a Shared or Semi-Isolated project, designers must use the Refresh command or reopen the assembly to update files that are referenced from the server.
Why would you use old versions of files?
Previous file versions can be restored when they are needed, but it is not possible to restore the previous state of an assembly.
The files in OldVersions\ are used for: