Attaching custom data to individual items (posts)

[Stefan Kyntchev]

Is there a good way to add a small piece of custom data to an individual item (for example an integer used as a bookmark in the associated podcast episode). The only thing I can think of is adding a custom "Tag" to the item, but that presents several issues related to modifying and cleaning unused tags. I was hoping that there could be something else (for example a comment/note/special tag) that can be attached to an item and retrieved back when loading the feeds items. There was at one time support for sharing and sharing with comment but those seem to have been deprecated after Google+ integration.

If adding a Tag is the only option, what is the most efficient way to clean "empty" tags (tags that have no items in them).

Stefan