Feature summary (what you would like to be able to do and where):

It should be possible to create statements linking to other files in Commons.

Use case(s) (list the steps that you performed to discover that problem, and describe the actual underlying problem which you want to solve. Do not describe only a solution):

It's not currently possible to store relationships between files, such as the ones represented by the use of templates like Template:Vector_version_available, Template:Extracted_from or Template:Archival_version, as structured data.

Benefits (why should this be implemented?):