Riesling is a white grape variety which originated in the Rhine region. Riesling is an aromatic grape variety displaying flowery, almost perfumed, aromas as well as high acidity. It is used to make dry, semi-sweet, sweet, and sparkling white wines. Riesling wines are usually varietally pure and are seldom oaked. (Google source)
Riesling with the ".io" extension, along with what it is ...I consider it relatively little value, in my little opinion