This read-create TruthValue controls whether low-numbered system ports are included in the port-sets computed for a MAP domain; normally ports below 2^(16-PSIDOffset) are excluded, and this setting is only meaningful when PSIDOffset is 0. An admin would only need to change this in a domain configured with no PSID offset, to decide if well-known ports get allocated to the customer's mapped port range. For example, with PSIDOffset at 0 and this set to false, ports 0-4095 remain reserved and unavailable to the customer's mapped IPv4 traffic.