Propertiesare Server-defined characteristics of Objects, DataVariablesand other Nodes. Propertiesdiffer from Attributesin that they characterise whatthe Noderepresents, such as a device or a purchase order. Attributesdefine additional metadata that is instantiated for all Nodesfrom a NodeClass. Attributesare common to all Nodesof a NodeClassand only defined by this specification whereas Propertiescan be Server-defined.

For example, an Attributedefines the DataTypeof Variableswhereas a Propertycan be used to specify the engineering unit of some Variables.

To prevent recursion, Propertiesare not allowed to have Propertiesdefined for them. To easily identify Properties, the BrowseNameof a Propertyshall be unique in the context of the Nodecontaining the Properties (see 5.6.3for details).

A Nodeand its Propertiesshall always reside in the same Server.