This read-create PortList specifies which source ports on the local (source) switch have their outbound (transmitted) packets mirrored into this RSPAN session for forwarding to the target monitoring station. Admins configure this separately from ingress mirroring to control whether they capture traffic leaving those ports, traffic arriving on them, or both. For example, an admin diagnosing why traffic sent out a specific uplink port looks malformed would enable egress mirroring on that port via this object to inspect the exact frames leaving it.