**Reason**:
- Extension hasn't been updated in almost a decade; only two wikis are listed as using it on WikiApiary, neither of which is reachable.
The extension's author updated its MediaWiki.org page in response to my notification, to remove the dead download links.
**To-do list**
- This task
-- [x] Add maintainers of that extension as subscribers to this task (if they have no apparent Phabricator account, notify them on-wiki or via email if possible and note it here). https://www.mediawiki.org/wiki/User_talk:Yedidia#Archival_of_Extension:ProtectedNotice
-- [x] Add Phabricator project <#ProjectX> as a tag for this task, or #mediawiki-extensions-other if there is no project.
- On-wiki documentation
-- [ ] Archive documentation on `mediawiki.org` (https://www.mediawiki.org/wiki/Extension:ProtectedNotice): replace page contents with `{{TNT|Archived extension|last revision id before archiving|reason=archive reasons}}`; include a link to this task in the `reason` parameter. If that documentation was translatable, remove `<translate>`, visit Special:PageTranslation, and click "remove from translation" (if you don't have the translation administrator right, ask a [[ https://www.mediawiki.org/wiki/Special:ListUsers/translationadmin | user who does ]]).
-- [ ] Archive Wikidata item associated with documentation page (https://www.wikidata.org/wiki/Q21678132) (remove nearly all statements, except `instance of (P31) = MediaWiki extension (Q6805426)`, which should add a qualifier `end time (P582) = the YYYY-MM-DD date that you decided to archive extension, generally per edit history`, change English (and other languages if possible) description to "archived MediaWiki extension" (and its translation)).
- Phabricator
-- [ ] ~~Archive Phabricator project <#ProjectX> for associated extension.~~
-- [ ] ~~Mark all Phabricator tasks for the extension/skin either Declined or Invalid.~~ (no tasks were ever filed for this extension, I think?)
-- [ ] ~~Edit Phabricator project <#ProjectX> description for associated extension with a link to this ticket.~~
- Translatewiki.net/translations
-- [ ] Remove from `translatewiki.net` (`groups/MediaWiki/mediawiki-extensions.txt`).
- Configuration/tests/integrations/etc.
-- [ ] Remove from `mediawiki/extensions` (along with in `.gitmodules`).
-- [ ] Remove tests in [[ https://gerrit.wikimedia.org/g/integration/config | `integration/config` ]] (`zuul/layout.yaml`).
-- [ ] Remove manifest/other references from `mediawiki/vagrant` if they exist.
-- [ ] Remove from https://doc.wikimedia.org/cover-extensions/ if present (requires #continuous-integration-infrastructure shell user to delete directly from the server).
- Repositories
-- [ ] Empty repository and add an ARCHIVED file.
-- [ ] Archive the extension's diffusion repository: (provide the Diffusion repository callsign or URL).
-- [ ] Mark the repository read-only in Gerrit: (provide Gerrit Repository URL).
-- [ ] Delete the GitHub mirror: (provide GitHub repository URL).