Manual:Page undeletion

Page restoration', or page undeletion, is done by Special:Undelete or API:Undelete. One or more revisions from the archive table are moved to the revision table and a new page entry, with a new is created. This entry's field will be set to 1.

Hooks

 * Manual:Hooks/ArticleUndelete, when one or more revisions of an article are restored