Yep it's tough to learn the lingo. It's even tougher to get whacked for it. But that's another story.

Jon is correct that the marker lights are actually "parking lights" when the headlights are not on. And as such, I only use them when "parked" with the engine running. If I deem it necessary to have them on while going down the road, I just turn the headlights on as well. I am sure some of the cab lizards will argue the point with me, but I will send them to Lew.

And Lew can tell you what they were called when they were mounted on dinosaurs. I'm sure the stegosaurus model was lit with LED's.