False {{used in system}}

SQL

select 
  dst.page_namespace,
  dst.page_title
from
  templatelinks
  join page dst on page_id = tl_from
where
  tl_namespace = 10 and tl_title = "Used_in_system"
  and (
    dst.page_namespace = 10
    or dst.page_namespace = 828
  )
  and not exists (
    select
      1
    from
      templatelinks tl2
      join page src on tl_from = src.page_id
    where
      tl2.tl_from_namespace = 8
      and src.page_title != "Deletedtext"
      and src.page_title != "Filedelete-success"
      /* these messages transclude their own talk page */
      and src.page_title not like "Ffeed%"
      /* while templates used on the main page are protected, they don't need to be tagged 
      as used in system, even though [[mw:Extension:FeaturedFeeds]] is installed */
      and src.page_title != "Category-move-redirect-override"
      /* not a system message in the normal sense */
      and src.page_title not like "Ipbreason-dropdown%"
      and src.page_title not like "Spam-%list/Indicators"
      and src.page_title != "Watcheditlist/Check_all"
      and src.page_content_model = "wikitext"
      and src.page_is_redirect = 0
      and src.page_title != "Move-redirect-text"
  )
  and dst.page_content_model != "sanitized-css"
  and dst.page_is_redirect = 0
SQL

Checking query status...
