Consider this example:<?php$zip = new ZipArchive;$zip->open(...);$zip->addFile('path/file', 'foo');$zip->renameIndex(0, 'bar');echo $zip->getNameIndex(0); // 'bar'$zip->unchangeIndex(0);echo $zip->getNameIndex(0); // 'false'?>Unless you call save() in between, the unchangeIndex() call reverts back to the initial state of the archive - where index '0' did not exist.If you called save() after addFile() and then renamed the file, you would be able to revert/undo the name change.