The IS215ACLEH1A module serves as the Application Control Layer Module within the GE Mark systems. It acts as a master controller, facilitating communication, monitoring, and control functions for various components within the system. This module is crucial for regulating the Automatic Voltage Regulator (AVR), Power System Stabilizer (PSS), Under Excitation Limiter (UEL), and Voltage/Power Factor (VAR/PF) through outer loop controls.