Each time Block is saved a new revision would be created by taking a snapshot from the Block fields. The following list represent the fields that are being copied while creating Block revision:
- Code
- Assignment Panel
So when a new revision is being created the Block code and all the assignment panel (Pages, Posts, Custom Posts, Aux, Urls and Expressions are being saved).
Currently, each Block is being saved up to 10 revisions. Block can be reverted to 10 times saves behind however take in your mind that all the other fields (Name, Order, Editor Language, Theme, etc…) cannot be restored as it doesn’t being saved anyway.
Revisions list is ordered in descendant order so that the last revision would be listed first. Once you select a revision CJT helps you look around first by checking if this revision is intended to be restored. The Block would get a read only copy of the Code and Assignment Panel values. You’ll notice that all those fields are disabled and the assignment panel is only showing the assigned Only items. You can discard that revision by click on ‘Cancel’ or save the reivision by ‘Restore’ it.
When the Revision is being cancelled CJT would take you to the last state just before you select the revision from the list however unlike restoring the revision would get a full copy of the revision and restoring the Assignment Panel to the initial/empty state.