To a disambiguation page: This is a redirect to a disambiguation page. This redirect is intended for use in links from other articles that need to refer to the disambiguation page, rather than be disambiguated. Therefore, this template should only appear on a redirect page that has "(disambiguation)" at the end of its title. Ambiguous titles that do not have page names ending with "(disambiguation)" should use {{R from ambiguous term}} instead. For disambiguations that later prove to still be ambiguous (e.g. "(painter)" when there are multiple notable painters by the same name) and which redirect to disambiguation pages, then {{R from incomplete disambiguation}} is the appropriate rcat template.
From a longer title: This is a redirect from a title that is a complete, more complete or longer version of the topic's name. It leads to the title in accordance with the naming conventions for common names and can help writing and searches. However, do not replace these redirected links with a piped link unless the page is updated for another reason.