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| An attribute is a string item listed in the attribute compartment of a classifier. An attribute defines an aspect or dimension of a classifier. An attribute may be assigned a value when an instance of a classifier is created. It is semantically equivalent to a classifier having a composite association with another classifier of the type specified in the attribute expression. |
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| A value of derived indicated by a forward slash (/) either prefixing the name or in isolation, indicates that the association end is derived. This means that its value can be calculated from other properties of the instance. |
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| A duration constraint is a type of interval constraint that specifies that one or more model elements must conform to a restriction specified by a duration interval. A duration constraint is not the duration interval itself but a constraint, which associates the interval with one or more elements, specifying how the interval restricts the duration semantics of the element(s). |
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| multiplicity is a property of an association end that specifies the number of instances of the classifier connected at the target end (near end) that can be associated with a single instance of the classifier at the source end (far end). It is specified in the form of a string stipulating a possible infinite number governed by a lower and upper bound. |
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| An association end is non-navigable if it is marked with an x. This icon is optional and is used to indicate that the classifier at the other end (source) of the association has no access to the classifier at the end (target) marked with the x. |
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| When the value of package is specified for the visibility property of an association end it signifies that any classifier that is contained in the same package as the association (or any nested sub package) may traverse the relationship and use the role name in expressions. |
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| A part is a property of a classifier and is used to represent the structural composition of a classifier. A part represents a set of instances either owned by the classifier or referenced by the classifier. The instances corresponding to its part may be created when the instance of the containing classifier is created or at some other point in its lifetime. When the containing classifier is destroyed all instances representing the parts are also destroyed. A part can declare a multiplicity, which indicates the allowable number of instances corresponding to the property (part) that can exist within the containing classifier. The multiplicity expression typically follows the name but may be placed in the top right hand corner of the part. Parts may be related to each other using connectors. |
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| A port is both a connectable element and a structural feature of an encapsulated classifier. A port specifies the way a classifier interacts with its external environment or the way the internal environment of the classifier provides services to its external environment. A port may be connected directly to other elements in its external environment but typically uses interfaces to declare either the services that it provides or the services that it requires. A port can be connected to the internal environment of the classifier by connectors. The connectors forward incoming requests to elements in the internal environment or outgoing requests to the ports. |
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| When the value of private is specified for the visibility property of an association end it signifies only the classifier connected at the source (far) end may traverse the relationship and use the role name in expressions. |
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| When the value of protected is specified for the visibility property of an association end it signifies that the classifier at the source (far) end of the association and its descendants may traverse the relationship and use the role name in expressions. |
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| When the value of public is specified for the visibility property of an association end it signifies that other classifiers in addition to the classifier connected at the source end of the association can traverse the relationship and use the role name in expressions. |
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| A stop is used to denote that a participant is destroyed during the lifetime represented by the diagram. The lifeline is ended indicating that the participant no longer exists; the dashed line ends in a small cross positioned at the end of the lifeline. A participant may stop itself. |
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| A terminate is a kind of pseudostate that stops the execution of the enclosing state machine. It can have one or more incoming flows but no outgoing flows. While a final state signifies that execution within the enclosing region is complete, a terminate ends the execution of the entire state machine including all regions contained within the machine. |
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| A time constraint is a type of interval constraint that specifies that one or more model elements must conform to a restriction specified by a time interval. A time constraint is not the time interval itself but a constraint, which associates the interval with one or more elements specifying how it restricts the elements, time semantics. |
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