A category is an identifier that you can assign to business rules and certain business elements (classes and members) in order to filter which business rules can use which business elements. A rule can use a business element if the rule category filter specifies at least one of the categories assigned to the business element. Only business elements that a rule can see appear in the rule editor drop-down list. You can assign one or more categories to Business Object Model (BOM) classes and members, or to a business rule category filter.