FAQ What are the functions of the standby/on/attenuator button? The standby/on/attenuator button serves as the power button and can also be used to reduce the volume.How do I select a specific CD track on the CD changer? Use the number buttons on the control panel to select the desired track on the CD changer.What do the RDS indicators on the display window indicate? The RDS indicators TP, PTY, AF, and REG3 provide information related to radio data system functionalities.