From OpenNMS

It's not immediately obvious to me what is meant by "NaV" in the sentence "The list of elements that can occur as a NaV are:". Net Asset Value? Does that mean something that can be assigned in the creation of the event? It might be more helpful to provide a definition or link to one here.

uei is listed as NaV, but uei is part of the eventconf.xml; so I believe this is the list of text substitutions available in notifications.