PCA Reference Data and Services

# Unit of Measure Context

## Purpose

Numeric values with units of measure related an object or a type objects are building blocks in plant design and operation. Such properties are used in multiple applications, datasheets and information handovers. The ISO 15926-14 approach to physical properties supports unambiguous data integration.

## Model content

The Unit of Measure Context modelling pattern takes line list information as an example. The blue 20L0123 is a process line individual. The process line has a pressure quantity, represented as the OWL individual 20L0123 pressure. The datum individual 70 barg separates the numerical value 70, in xsd:decimal data type, from the unit measure, bar gauge.

Pressure Datum, Nominal Datum, and Operating Datum are all part of the RDL vocabulary, made available to provide context to the values with units. These are important for integration between applications and organisations. In the bottom part of the diagram, it is shown how OWL object properties and data properties should be used to efficiently manage numeric properties as they are commonly found in data sheets and similar contexts.