I had to look it up also....What do you do with them after you rake them up?
A few years back, I tried filling 30 gal bags with the shredded leaves from the Trac-Vac and loading the bags into my garbage cart.
That lasted one week and they sent me a letter saying I would no longer be a customer if I did it again.
Apparently tree leaves don't break down/decompose like plastic or styrofoam does.