Hi All,
I was surprised to realize that you cannot include this info within a Schedule - I'm coming from the Architecture side where most custom families can have a room/space selection. Another workaround, depending upon the data you need, would be to use a Multi-Category schedule and filter on Category=Duct Accessories. See here for more detail:
http://screencast.com/t/ACk9YsqxHGVY
Of course the downside of using Multi-Category is that you may not have access to all the parameters you need, just thought I'd throw it out there.