Noindex

The noindex value of an HTML robots meta tag requests that automated internet bots avoid 'indexing' a web page. MediaWiki applies noindex to special pages by default. Other pages can be designated as noindex as well, depending on. Encyclopedia Dramatica does not apply noindex to its edit pages and diffs; therefore, raw wikitext could theoretically show up in  results, and old revisions do indeed sometimes show up in search results.