# Primary Attribute

RIB uses the primary attribute to categorize object in your repository's catalog. The primary attribute must be contained in the primary class, and it must use a controlled vocabulary. It should also be a required attribute, though this is not enforced. An object without a value for this attribute will appear in the top level of the catalog. If an object has more than one value for the primary attribute, it will appear in each of the corresponding categories in your repository's catalog.

The "Change" button for the primary attribute is located under the "Manage Catalog" tab. Note that changing the primary attribute will cause any objects currently linked into the catalog as a result of interoperation to disappear. The next time that the interoperations are updated, your repository will categorize remote objects according to the new primary attribute. If the value of the primary attribute in a remote object does not appear the your primary attribute's vocabulary, RIB will use a depth first search to look for the nearest match. If a match is not found, the object will appear in the top level of your catalog.

See the help documentation on Repository Properties / Data Model Editor for information on controlled vocabularies and required attributes.