Ports represent interaction points through which a Classifier communicates with its environment.

The Interfaces associated with a Port specify the nature of the interactions that may occur over it. The required Interfaces of a Port characterize the requests that may be made from the EncapsulatedClassifier to its environment through this Port.

The Port Requires (Uses) Interface is drawn from a Port to an Interface. In the example below, the relationship is drawn from the Port on Engine, to the Interface definition, Transmission.

The full example, combined with the Provided Interface side, is: