Class
The class of a type describes whether the type represents a simple data object (item), a complex data object (group), or whether is used to organize types (category). Define the class of the selected type by selecting the check box.
- Category
- Categories organize types that have common properties. Each category has a set of
item properties and a set of group properties. Subtypes of the category inherit these properties.
A category does not define data objects in detail. A category type may be a component of a partitioned group, after a component with the identifier attribute. A category cannot be a component of a non-partitioned group.
- Item
- The item type represents a simple data object that does not consist of any objects. An item does not have components.
- Group
- The group type represents a complex data object that consists of components.
To change a type's class, select the type and choose the desired class in the Properties window.
If you change a type to an item, all the types in its subtree become items. If you change a type to a group, all the types in its subtree become groups. This is because the schema has a classification hierarchy and all the nested subtypes of an item must be items. Similarly, all the nested subtypes of a group must be groups.