It has no lockout.

There's a red dial that has 7-position rebound dampening, and there's a 3-position lever for "floodgate" which it seems by my experiments (RockShox gives you NO documentation on how the shock works) to set the threshold at which the shock reacts to bumps. "Min" means it responds to just about anything (including some pedalling) and "max" means it has to take a large hit in order to trigger movement. I picked the setting in the middle which seemed to ignore my pedalling but still soak up most bumps.

But the lever is easy to reach from the riding position, and a quick flip to "min" just before a bumpy descent seems to work really well.

I think I need another 10 lbs or so of air pressure, as I set the sag without my gear on, and I carry a 100oz cameback with a few tools in it. But it definitely keeps the rear end of the bike in place way better than the old Vanilla.