This read-only value indicates which physical or logical port a given CES channel is mapped to, though its exact meaning differs by card: on CESM-4P it follows a fixed formula where port 1 maps to channel 16, port 2 to channel 17, and so on, while CESM-8P uses cesChanPortNum instead of this object for its channel-to-port mapping. An administrator on a CESM-4P card uses this predictable mapping to identify which of the four physical ports a channel number corresponds to without needing a separate table. For example, seeing channel 18 on a CESM-4P immediately tells the operator it belongs to physical port 3 per the fixed mapping.