C1.1 OBA represents a battery of Guns outside the area represented by the mapboard, using radio-directed Indirect Fire to fire HE or SMOKE (or IR) onto designated areas of the mapboard. OBA availability is usually symbolized by the presence of a radio counter in the scenario OB and is further defined by SSR or DYO purchase as to type.
Each radio in the OB represents one predesignated available OBA battery (aka module). Each battery may produce a variable number of Fire Missions, but only via the one radio representing it in the scenario. If that radio is lost, so is the opportunity to contact that battery; another radio may not be used to call in the remaining Fire Missions of that battery