Manage Categories for Types of Entities
You can use categories for your entity types to group similar entity types into one group.
For example, you can have an entity category (like Aircraft) and then define specific entity types within that category (for example, light plane or microlight). You can also specify relationships of entity categories with other entity categories and types.
The Details tab of the screen for all entity types shows the category. The category is optional for all types except user-defined (miscellaneous) types.