Metrological support for quantities and units in digital systems

Unit systems and dimensions emerged in the late 19th century. However, efforts to adapt these ideas for use in modern digital systems are proving a challenge. We provide an interpretation of units and dimensions that clarifies the main reasons for difficulties. We then suggest how a digital system would provide adequate support for quantities and units. A layer of metrological information is envisaged that would track details and allow familiar unit formats to be rendered. Three independent aspects of the data should be captured: 1) the quantity; 2) the measurement scale, scale type and conversion functions; and 3) the semantics of numerical data