If you delete a named item, view Global history, click the HIST link for the deleted item (see
#462) to view item history, then click the revert link for the latest version (which will be a nameless revision)...
On the basic theme the "item not found" will be displayed -- the user will be led through the dialog to create a new item with the item ID as a name.
On the modernized theme, the user may add a comment and revert the item -- a new nameless revision will be created. The net result is the item is still sort of deleted, although the last action may be shown as a revert.
A guess is the proper action for both themes is to not show the Revert option for any nameless revision.
Complicating factors may be tickets and blogs. There does not appear to be a way to delete tickets, have not tried blogs.