I can’t remember if I’ve put something out publicly, but I think media objects (blobs) in particular should usually have license and attribution metadata attached when designing lexicons.
Two metadata fields:
licenseUri: string, format=uri, optional. standard/normalized URL(or short URI) for common licenses, or can point to more bespoke license/policy pageattribution: string, optional: more free-form field for listing a name or source of the media. can also be a URI that links back to the original source
These fields would go alongside things like alt-text. If there are multiple pieces of media in a record, it should be possible to attach different metadata to each (same as with alt-text).