Indicate that the application is prepared to attempt a restore of any backed-up dataset, even if the backup is apparently from a newer version of the application than is currently installed on the device. Setting this attribute to true will permit the Backup Manager to attempt restore even when a version mismatch suggests that the data are incompatible. Use with caution!

The default value of this attribute is false.

Must be a boolean value, either "true" or "false".

This may also be a reference to a resource (in the form "@[package:]type:name") or theme attribute (in the form "?[package:][type:]name") containing a value of this type.

[Android Documentation]