An association is composed of two AssociationEnds. Each AssociationEnd defines a Classifier participant in the Association, the role it plays, and constraints on sets of the Classifier instances participating. An instance of an AssociationEnd is a LinkEnd,
which defines a relationship between a link, in instance of an Association, and an instance of the AssociationEnd's Classifier, provided in its type attribute.

Attributes
Class	aggregation	Certain associations define aggregations - directed associations with additional semantics. When an AssociationEnd is defined as composite or shared, the instance at 'this' end of a Link is the composite or aggregate, and the instance at the 'other' end is the component or subordinate..
Primitive Type boolean	isChangeable	The isChangeable attribute restricts the capability to perform actions that would modify sets of instances corresponding to this AssociationEnd (the same sets to which multiplicity is applied). Specifically, the set may be created when the instance defining the set - the instance at the opposite end of the Links - is created. This attribute does not make the set immutable. Instead, it affects the generation of operations in Model Elaboration which would allow modification of the set. For IDL generation, the only operation that allows the set to be modified would be one or more factory operations that create the instance and create the set. The modeler is free to define specific operations that allow modification of the set. Note that defining this AssociationEnd with isChangeable equals false places restrictions on the changeability of the other AssociationEnd, due to their interdependence.
Primitive Type boolean	isNavigable	The isNavigable attribute determines whether or not the AssociationEnd supports link 'navigation'. This has two implications: A Class defined with an appropriate Reference supports navigation of links from one Class instance to another. If isNavigable is false for an AssociationEnd, no such References may be created. Setting isNavigable to false also suppress a mapping’s mechanisms for indexing links based on this AssociationEnd.
Class	multiplicity	Multiplicity defines constraints on sets of instances. Each instance of the Classifier defined by the opposite AssociationEnd's type defines a set which this multiplicity attribute constrains. Given one of those instances, x, the set is defined as the instances connected by LinkEnds of this AssociationEnd to that instance x. In its use is describing AssociationEnds, isUnique has been constrained to be true, as a simplification. This constraint means that the same two instances cannot participate in more than one Link while participating under the same AssociationEnd. Normally, two instances cannot be linked by more than one Link of an Association at all. But when the AssociationEnd types allow the two instances switch ends, they can form a second Link without violating the isUnique constraint.
Primitive Type string	qualifierName

 aggregation

public Class aggregation

Certain associations define aggregations - directed associations with additional semantics. When an AssociationEnd is defined as composite or shared, the instance at 'this' end of a Link is the composite or aggregate, and the instance at the 'other' end is the component or subordinate..

Properties:

Aggregation	none
Alias
Association
Association End
Class	Class AssociationEnd
Collections
Datatype
Default
Default Value
Is Composite	false
Is Derived	false
Is Derived Union	false
Is Leaf	false
Is Ordered	false
Is Read Only	false
Is Static	false
Is Unique	true
Keywords
Lower	1
Lower Value
Multiplicity	1
Name	aggregation
Name Expression
Opposite
Owned Template Signature
Owner	Class AssociationEnd
Owning Association
Owning Parameter
Qualified Name	model1::model1::AssociationEnd::aggregation
Stereotype
Template Parameter
Type	Class
Upper	1
Upper Value
Visibility	public

 isChangeable

public Primitive Type boolean isChangeable

The isChangeable attribute restricts the capability to perform actions that would modify sets of instances corresponding to this AssociationEnd (the same sets to which multiplicity is applied). Specifically, the set may be created when the
instance defining the set - the instance at the opposite end of the Links - is created. This attribute does not make the set immutable. Instead, it affects the generation of operations in Model Elaboration which would allow modification of the set. For IDL generation, the only operation that allows the set to be modified would be one or more factory operations that create the instance and create the set. The modeler is free to define specific operations that allow modification of the set. Note that defining this AssociationEnd with isChangeable equals false places restrictions on the changeability of the other AssociationEnd, due to their interdependence.

Properties:

Aggregation	none
Alias
Association
Association End
Class	Class AssociationEnd
Collections
Datatype
Default
Default Value
Is Composite	false
Is Derived	false
Is Derived Union	false
Is Leaf	false
Is Ordered	false
Is Read Only	false
Is Static	false
Is Unique	true
Keywords
Lower	1
Lower Value
Multiplicity	1
Name	isChangeable
Name Expression
Opposite
Owned Template Signature
Owner	Class AssociationEnd
Owning Association
Owning Parameter
Qualified Name	model1::model1::AssociationEnd::isChangeable
Stereotype
Template Parameter
Type	Primitive Type boolean
Upper	1
Upper Value
Visibility	public

 isNavigable

public Primitive Type boolean isNavigable

The isNavigable attribute determines whether or not the AssociationEnd supports link 'navigation'. This has two implications:

• A Class defined with an appropriate Reference supports navigation of links from one Class instance to another. If isNavigable is false for an AssociationEnd, no such References may be created.


• Setting isNavigable to false also suppress a mapping’s mechanisms for indexing links
  based on this AssociationEnd.

Properties:

Aggregation	none
Alias
Association
Association End
Class	Class AssociationEnd
Collections
Datatype
Default
Default Value
Is Composite	false
Is Derived	false
Is Derived Union	false
Is Leaf	false
Is Ordered	false
Is Read Only	false
Is Static	false
Is Unique	true
Keywords
Lower	1
Lower Value
Multiplicity	1
Name	isNavigable
Name Expression
Opposite
Owned Template Signature
Owner	Class AssociationEnd
Owning Association
Owning Parameter
Qualified Name	model1::model1::AssociationEnd::isNavigable
Stereotype
Template Parameter
Type	Primitive Type boolean
Upper	1
Upper Value
Visibility	public

 multiplicity

public Class multiplicity

Multiplicity defines constraints on sets of instances. Each instance of the Classifier defined by the opposite AssociationEnd's type defines a set which this multiplicity attribute constrains. Given one of those instances, x, the set is defined as the instances connected by LinkEnds of this AssociationEnd to that instance x. In its use is describing AssociationEnds, isUnique has been constrained to be true, as a simplification. This constraint means that the same two instances cannot participate in more than one Link while participating under the same AssociationEnd. Normally, two instances cannot be linked by more than one Link of an Association at all. But when the AssociationEnd types allow the two instances switch ends, they can form a second
Link without violating the isUnique constraint.

Properties:

Aggregation	none
Alias
Association
Association End
Class	Class AssociationEnd
Collections
Datatype
Default
Default Value
Is Composite	false
Is Derived	false
Is Derived Union	false
Is Leaf	false
Is Ordered	false
Is Read Only	false
Is Static	false
Is Unique	true
Keywords
Lower	1
Lower Value
Multiplicity	1
Name	multiplicity
Name Expression
Opposite
Owned Template Signature
Owner	Class AssociationEnd
Owning Association
Owning Parameter
Qualified Name	model1::model1::AssociationEnd::multiplicity
Stereotype
Template Parameter
Type	Class
Upper	1
Upper Value
Visibility	public

 qualifierName

public Primitive Type string qualifierName

Properties:

Aggregation	none
Alias
Association
Association End
Class	Class AssociationEnd
Collections
Datatype
Default
Default Value
Is Composite	false
Is Derived	false
Is Derived Union	false
Is Leaf	false
Is Ordered	false
Is Read Only	false
Is Static	false
Is Unique	true
Keywords	list
Lower	1
Lower Value
Multiplicity	1
Name	qualifierName
Name Expression
Opposite
Owned Template Signature
Owner	Class AssociationEnd
Owning Association
Owning Parameter
Qualified Name	model1::model1::AssociationEnd::qualifierName
Stereotype
Template Parameter
Type	Primitive Type string
Upper	1
Upper Value
Visibility	public

• An association is composed of two AssociationEnds. Each AssociationEnd defines a Classifier participant in the Association, the role it plays, and constraints on sets of the Classifier instances participating. An instance of an AssociationEnd is a LinkEnd,
  which defines a relationship between a link, in instance of an Association, and an instance of the AssociationEnd's Classifier, provided in its type attribute.