Final answer:
A regulator opens the RCCR points in the 12V generator system to control the charging process and prevent battery overcharging.
Step-by-step explanation:
A regulator is the component that opens the RCCR points in the 12V generator system. The full form of RCCR is 'Regulated Charge Control Relay', and it is a part of the charging system in vehicles. The regulator controls the current flow within the generator and maintains a constant voltage level within the electrical system. When the voltage in the system exceeds a predetermined level, the regulator opens the RCCR points (contacts) to prevent overcharging of the battery. The RCCR then breaks the circuit, which stops the generator from producing current until the voltage drops to a safe level and the points close again, resuming charging.