I know that you can technically do this with the “Genre” section in most media, but there are functions that look for matches there that run counter to what I am hoping to be able to do.
Primarily I am looking for a field for custom data tagging that does not get read in any other definitions. For example, I would like to mark TV series as “Series Completed” when they end their run, or movies being a “Remake”. Maybe others would like to note certain favorite tropes that fall outside of Genre. These don’t actually fit as genre definitions, but they can be useful to have for smart categories or just running general searches when managing libraries.