Thank you so much for your reply, Jeremy
Here is the problem I anticipate users having:
User imports autocad 2D backgrounds, with everything on one layer (converted from a pdf to dwg)
The dwg background has millions of elements, he just needs to keep the ceiling HVAC diffusers.
User identifies the diffusers have a certain line length, so instead of painstakingly manually selecting them for multiple days, it could be accomplished by selecting elements with line length property greater than a certain tolerance, and lesser than a certain tolerance, then remove any artifacts, taking maybe 15 minutes instead of something like 12 work hours.
However, Revit appears to only allow selecting by category, without selecting by properties within these categories. This seems lacking considering Revit is supposedly a database of data, the data of the element properties should be accessible by now, Revit has been out a while.. What am I missing if this is not even available in the API?