I am sure you know sake is made with water and the nihonshu-do, or the sake meter value is a measure of the density of the sake relative to water. It is a very general reference to the sweetness or dryness of a sake. Note, however, that acid content and water hardness and temperature and other factors also contribute a great deal to the concept of sweet and dry. The smv is the specific gravity measured on a scale weighing the same volume of water at 4°C and sake at 15°C. The sweeter the sake, the lower the number. When the smv was first used, 0 was designated the point between sweet sake and dry sake. Now +3 is considered neutral.