document versioning

During my regular backups, I recall distinctly seeing that InDesign had saved my documents in previous states -- maybe half a dozen for each doc in a book. I even opened one to recapture some lost text. This occurred within the last two years. Since then I have gone happily along (doing regular backups) but also in the understanding that InDesign was saving usable previous states of my documents in a folder called -- if I remember correctly -- versions.

This feature seems to have disappeared. I only noticed it because I didn't see it during my backup.

Does anyone else remember this? Can you direct me to where this was being saved or tell me how to set it up again? (ID has been through a version or two since then.)

Thanks.

-j