A&E COM browsing yields a hierarchy of areas and sources. Areas can contain both sources and other areas in tree fashion where areas are the branches and sources are the leaves. The A&E COM UA Proxy relies on the "HasNotifier" Referenceto assemble a hierarchy of branches/areas such that each Object Nodewhich contains a HasNotifier Referenceand whose EventNotifier Attributeis set to SubscribeToEventsis considered an area. The root for the HasNotifierhierarchy is the Server Object. Starting at the Server Object, HasNotifier References are followed and each HasNotifiertarget whose EventNotifier Attributeis set to SubscribeToEvents becomes a nested COM area within the hierarchy.

Note that the HasNotifier target can also be a HasNotifier source. Further, any Nodewhich is a HasEventSource source and whose EventNotifier Attributeis set to SubscribeToEvents is also considered a COM Area. The target Nodeof any HasEventSource Referenceis considered an A&E COM “source” or leaf in the A&E COM browse tree.

In general, Nodes which are the source Nodes of the HasEventSource Referenceand/or are the source Nodes of the HasNotifier Referenceare always A&ECOM Areas. Nodes which are the target Nodes of the HasEventSource Referenceare always A&E COM Sources. Note however that targets of HasEventSource which cannot be found by following the HasNotifier References from the Server Objectare ignored.

Given the above logic, the A&E COM UA Proxy browsing will have the following limitations: Only those Nodes in the UA A&C Server’s address space which are connected by the HasNotifier Reference(with exception of those contained within the top level Objects folder) are considered for area designation. Only those Nodes in the UA A&C Server’s address space which are connected by the HasEventSource Reference(with exception of those contained within the top level Objects folder) are considered for area or source designation. To be an area, a Nodeshall contain a HasNotifier Referenceand its EventNotifier Attributeshall be set to SubscribeToEvents. To be a source, a Nodeshall be the target Nodeof a HasEventSource Referenceand shall have been found by following HasNotifier References from the Server Object.