A Quantity describes a physical dimension by exponents of the available attributes.<br/><br/>Some examples of Quantity are:<br/>name = "Length" and lengthExp = "1"<br/><br/>name = "Angle" and all attribues = 0, i.e. angle is without dimension.<br/><br/>name = "Acceleration" and lengthExp = 1 and timeExp =-2.<br/><br/>Semantics:<br/>The Quantity describes a physical dimension for use in numerical datatypes and expressions to facilitate dimension consistency and control.<br/>