To figure out what is going on, go into Navisworks Options - Interface - Developer and tick the two boxes:
Show Internal Properties
Show Property Internal Names
Now, when you use the Properties palette you will see additional information in brackets, which essentially amounts to the Navisworks 'internal parameter name' for a given piece of data. Pretty cool!
Thanks for this tip goes to Jason Howden, from RTV Tools, a Platinum sponsor here at What Revit Wants.
Related forum post: