Semi Boneless Leg Of Lamb?

Can anyone tell me what semi boneless means? It has a bone in it.
Anyway, I picked up a semi boneless leg of lamb on sale and thought I would experiment. I will probably season with kosher salt, black pepper, garlic, and fresh rosemary. I debated on whether to cook it in the UDS or one the Weber kettle. I am thinking Weber kettle indirect to IT of 135. Should I remove the bone prior to cooking or cook it bone in? Any advice would be appreciated.