Spotlight is a rather neat feature once you get beyond the simple text search interface and use the more advanced search in the Finder. However, Apple don’t allow users to add their own metadata to files, so you’re limited to searching for data which exists within the files and is exposed by the importers. Ben Summers did some investigation and worked out how to add arbitrary and independent metadata to the Spotlight store.
SpotMeta Lets Spotlight Users Add Metadata
Submitted by G.S. 2005-10-10 macOS 4 Comments
You can add comments to every file via the finder, or via Automator. Just create an automator action which will add spotlight comments to any file, and boom it shows up based on that Spotlight info.
You can see a file’s spotlight comments via “get info” in the finder