Event Sources in the A&E COM Server are represented in the A&E COM UA Wrapper as Objects with a TypeDefinition of BaseObjectType. If the A&E COM Server supports source filtering then the SubscribeToEvents flag is True and the Source is a target of a HasNotifier Reference. If source filtering is not supported the SubscribeToEvents flag is False and the Source is a target of a HasEventSource Reference.

The Sources are discovered by calling BrowseOPCAreas and the GetQualifiedSourceName Methods. The Source name returned by BrowseOPCAreas is used as the BrowseName and DisplayName. The QualifiedSourceName is used to construct the NodeId. Event Source Nodes are always targets of a HasEventSource Reference from an Area.