3.1.1.3.3 Configuration Collections
Configuration collections are special configuration elements that serve as containers, where elements inside them are considered to be part of a set that can be dynamically added and removed. Elements in these containers are also known as collection items. A configuration item can also contain child elements and configuration properties. The items contained in a configuration collection don't have to be uniquely named and they share the same schema (see section 3.1.1.3.5).
Configuration items as members of configuration collections are structurally the same as configuration elements but semantically represent operation on the collection. These operations include such as add element, remove element, or clear the collection.
The name of the collection item is the directive. By default, the directives are add, remove, and clear. However the configuration schema allows these names to be overridden for a collection. It implies from the above that collection item names are not unique within a collection.
The configuration properties in a collection item describe additional data consumed by the operation.
Configuration schema can be used to establish uniqueness and other constraints on a configuration collection.