Model, Component, and Package Management > Package management > Overview of packages > Overview of packages
  
Overview of packages
Packages allow you to organize items and diagrams in a Model. By adding Packages to other Packages, you can create a Package hierarchy in a Model. Through the Packages pane, you can quickly maintain the Package hierarchy and the content of each Package through drag-and-drop operations.
In addition to scoping (packaging) items, Packages:
Specify the access permissions of the items they contain. For more information about Model item access permissions, see Overview of model item access permissions.
Provide configuration management control to the items they contain. For more information about using Modeler with configuration management tools, see Overview of configuration management tool integration (CM tool integration).
Ensure that you consider security and source control needs when creating a Package hierarchy in a Model.
All items in a Model are packaged, either by a Package or by the Model itself. Most items can be directly packaged, but some items are packaged through parent items:
Items that can exist independently of other items and diagrams can be scoped directly by a Package. For example, an Actor or Class.
Items that can exist only as a child of another item are scoped by the Package that scopes their parent item. For example, a Column is scoped by the Package that scopes its parent Table.
Items that appear on diagrams and not in the Modeler panes (for example, a Timing Constraint) are scoped through the Package that owns the diagram on which they appear.
Items that can exist only as a child of two or more items (link items) are scoped by either the Package that scopes the source or destination item. For example, an Association is scoped by the Package that scopes the source Class. For information about a specific link type, see the Reference section of the Help.
Diagrams that are owned by a Model item are scoped by the Package that scopes the owning item.
You can order a Package's items through the Items tab of the Package's Property Pages - select All Package Items in the drop-down list, and then use the buttons to order the items as required. Alternatively, when the Show Package Items Sorted command on the View menu is turned off, you can right-click an item in the Packages pane, and then click Move Up or Move Down.
When you use a Package to scope an item, you are creating a link between the Package and that item. Like other links, you can create the links through drag-and-drop operations in the Modeler panes, and through the Links Editor.
Within a Package, the name of each item that is scoped directly by the Package must be unique. This is not the case when items are scoped directly by the Model, in which case items of different types can have the same name. For more information, see Name (property).
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When you delete a Package, Modeler deletes the Package and all items scoped by that Package.
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If you create an item on a diagram, the item is scoped by the Package that scopes the diagram.
An item cannot be scoped directly by both a Package and a Subsystem.
The full name of an item typically shows the name of the Packages that scope the item. For example, If Class1 is scoped by Package1, the full name of the Class is Package1::Class1.