A call event models the receipt by an object of a message invoking a call of an operation.

A slot specifies that an entity modeled by an instance specification has a value or values for a specific structural feature.

A trigger relates an event to a behavior that may affect an instance of the classifier. A trigger specification may be qualified by the port on which the event occurred.

An instance specification is a model element that represents an instance in a modeled system.

An instance specification has the capability of being a deployment target in a deployment relationship, in the case that it is an instance of a node.

It is also has the capability of being a deployed artifact, if it is an instance of an artifact.