Dimensionless Any unit or combination of units that has no dimensions. A Dimensionless Unit is a quantity for which all the exponents of the factors corresponding to the base quantities in its quantity dimension are zero. Dimensionless QUDT http://qudt.org/schema/qudt#DimensionlessUnit ODM2 Units Type Controlled Vocabulary ODM2 Working Group A vocabulary for describing the type of the Unit or the more general quantity that the Unit represents.