The word "port" implies an external connection to a peripheral device, whereas "slot" generally refers to an internal bus connection. For example, USB and Ethernet ports are sockets on the outside of the computer case that a cable plugs into.

Slot  means the space occupied by one 20' x 8' x 8'6  ISO container for the predetermined maximum average gross weight. The Loading Party  means the Party on whose vessels (owned and/or operated) the containers are loaded. The Shipping Party  means the Party who is shipping containers on the other Party's vessels.