The File Canonical extension for TYPO3 CMS provides canonical links (via HTTP headers) for files (e.g. in fileadmin/). This allows you to define a page, related to the requested file, which might be important for SEO.
Read more about: Canonical tags in HTTP headers
Screenshot: Info module overview
This extension has been supported by Institut der deutschen Wirtschaft Köln Medien GmbH
The File Canonical extension provides a ReST documentation, located in Documentation/ directory.
You can see a rendered version on https://docs.typo3.org/p/t3/file-canonical/main/en-us/