Architecting and designing : UML 2.5 : Relationships : Package Containment
  
Package Containment
Package Containment means that one Package contains the other, or is nested in the other.
Containment means the containing Classifier does not directly expose the contained Classifier. The Containing Classifier exposes its own interface and may call on the contained Classifier on behalf of the client.
So there is no way for the client to mess with the contained Classifier. The containing Classifier owns the contained Classifier. Example: a restaurant where you order food, and the waiter places your order, the chef cooks the dinner, and it is presented to you.
Relates
The Package Containment relationship can be drawn like this:
From
To
Package
Package
Example
This graphic is described in the surrounding text.
See also
Association
Dependency
Realization
Collaboration Property to Part
Component Provides (Realizes) Interface
Component Requires (Uses) Interface
Port Provides (Realizes) Interface
Port Requires (Uses) Interface
Comment to AnnotatedElement
Constraint to ConstrainedElement
Connector
ElementGroup to Element
Instance Specification Relationships
Generalization
Package Import
Substitution
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Relationships