In many cases the data of features, sensors and observations we are interested in is data of physical quantities. Therefore property structures can contain properties of type Quantity that allow for unambiguous storage exchange and processing of numeric data that represents physical quantities.

This chapter gives a general overview on physical quantities, unit systems and units and shows how physical quantities are handled by Redbex. It also lists the quantities, units and unit systems that are actually supported by the Application Server i.e. that can be used by properties in property structures. Note that new quantities, unit systems and units may become available with the Online Data Update.

The implementation of Quantities in Redbex is designed upon the International System of Units (SI) but also provides support for units originating form other unit systems. Refer to [4] for more details on the SI system.