For the Platform Manager (and Power Manager II) devices, each VMON input has an A and B trip point setting. The A trip point is the Over-Voltage (OV) trip point the and the B is the Under-Voltage (UV) trip point.
In the standard mode: The A signal will be 1 when the input voltage exceeds the OV trip point, otherwise it is 0. The B signal will be 1 when the input voltage exceeds the UV trip point, otherwise it is 0.
In the Window mode: The A signal will be 1 when the input voltage is between the UV and OV trip points, otherwise it is 0. The B signal will be 1 when the input voltage exceeds the UV trip point, otherwise it is 0.
Please note the B signal works the same in either mode. In the Window mode most times you can just monitor the A signal since it changes state whenever the input value is outside of the normal range (called the Window).