Checking Out an Old Version of an Object Definition

From the object definition's Version History page:

1. Navigate to the object definition in its Domain or Application Area, either in the Applications screen or by clicking the link to the definition in an instance of it.
2. From the Actions drop-down list, select View Version History. The Version History screen opens; see Version History.
3. Select the version you want to check out and click Check Out. The system creates a new version of the object based on the one you checked out, with a version number that is equal to the latest version's number plus one. All the changes you make apply to the new version.