There are two types of management packs:

• Sealed management packs: A sealed management pack (.mp file) cannot be modified.
  
  
• Unsealed management packs: An unsealed management pack (.xml file) can be modified.
  
  

Other than lists and forms, objects such as views that are defined in a sealed management pack cannot be customized. Customizing a list that is defined in a sealed management pack includes adding list items. Customizing a form that is defined in a sealed management pack includes adding fields. The customizations to lists and forms that are defined in a sealed management pack must be stored in an unsealed management pack.

You cannot unseal a management pack that is sealed. To modify objects that are stored in a management pack which you have already sealed, you can modify the original unsealed management pack file from which the sealed management pack was created. Then, re-seal the changed management pack.

A model management pack is a management pack that contains definitions for basic objects such as classes, combination classes, and relationship types.

Building model management packs allows other customizations, typically related to presentation such as templates, views, and tasks, to be stored in separate management packs that depend on the model extensions. Additionally, model management packs are easily transferred into the data warehouse for archiving and reporting purposes.

A management pack can depend on another management pack which is sealed. For example, a custom template in one management pack can depend on a list that is defined in another management pack. The management pack that contains the base definitions, such as the list, on which other definitions need to depend on – must be sealed. A management pack can also require resources such as a form or an image that are stored separately.

When deploying a management pack that has resource requirements, you must bundle the required resources and the management pack into a single management pack file that can be imported into Service Manager.

In addition, if the management pack has dependencies on other management packs, those dependent management packs must be imported first. Alternatively, you can bundle the dependent management packs along with the required resources and the depending management pack.

For more information about how to bundle a management pack with its resources and dependent management packs, see the Introducing Management Pack Bundles blog.

You might have to customize and extend the default pre-imported management packs so that IT professionals and other users in your organization can extend existing solutions and customize them to meet your business and customer needs. To customize features in Service Manager, you can add new objects or modify the objects that are related to that feature.

A customization to an object is a modification that applies to the base definition of the object. To be able to apply customizations to a base definition, the base definition must be stored in a sealed management pack. And because it is not possible to save customizations in the sealed management pack that contains the object’s base definition–you always have to use or create another, unsealed management pack to store customizations.

Typically, when customizing objects from a default pre-imported management packs, you work with two management packs. The first is the sealed management pack that contains the base definitions of objects, and the second management pack, that is initially unsealed, and that contains the customizations to the base object. In this case, the management pack with the customization depends on the management pack that contains the base definition of the object.

When customizing objects that are defined in an unsealed management pack, you can use the same management pack to store the customizations.

After you complete the customizations, you can deploy them by importing the management pack to Service Manager. During import of a sealed management pack, Service Manager synchronizes the Service Manager database and the data warehouse database with the definitions from the management pack. During import of an unsealed management pack, other than list definitions, Service Manager synchronizes only the Service Manager database with the definitions from the management pack. List definitions in an unsealed management pack are synchronized to both databases.