Note that "NAT translations" (for IP) actually use a combination of five different fields (a "5-tuple"): source IP address, source port, destination IP address,

Note that "NAT translations" (for IP) actually use a combination of five different fields (a "5-tuple"): source IP address, source port, destination IP address, destination port, and protocol. This means that you aren't limited to, for example, 65,535 TCP sessions on a single host even though there are only that many ports available.