Talk:Windows X X/@comment-35134374-20190402125251/@comment-35134374-20191104171533

This isn't that notion. It's:
 * 1) Finite years (-oo to oo)
 * 2) Old post-oo
 * 3) X of Y
 * 4) xø and accented empty set versions
 * xEy
 * 1) x/.y