ZxBackup restoration procedure for ZImbra server customizations?

Iiuc, a Zimbra upgrade, even a minor point update e.g. 8.0.0 -> 8.0.1, *may* overwrite any Zimbra customizations applied on the server by the user.

Zextras 1.6.3 offers (Changelog - ZeXtras Suite Wiki) as a new feature,

The last step of both Export and *Scan operations now saves a copy of the Zimbra customizations applied on the server along with the server config.

Is the ZxBackup v1.6.3 procedure documented for restoring, or at least diff-ing/comparing, just the Zimbra *server* customizations after a Zimbra upgrade?

-rb