Forms done in the air, techniques done against a wooden platform, and rolling hands in a manner that cannot be done for real.
---What about Thai boxers "shadowboxing", BJJ or wrestlers practicing the sprawl and other things solo...those are a type of "forms done in the air." What about Thai boxers working the pads or the heavy bag, or grapplers practicing with a grappling dummy....those are a type of "technique done against" something. And I still don't think rolling with a training partner in the gym as any different than doing Chi Sao. That is...if the Chi Sao is done properly.