What does USD mean on a motorcycle?

I've been looking at motorcycles on Craigslists, and I keep seeing "USD" - I know that can mean US Dollars, but it doesn't make sense in the context it was found. What does it mean?|||USD stands for upside down forks on a motorcycle. With USD's, the slider tubes are at the bottom of the forks, which decreases the unsprung weight and improves handling. They are also called Inverted Forks.|||Probably means UpSide Down, referring to the front suspension|||USD usually means US dollars but it could mean"used".So called up side down forks are listed as inverted forks.