Use access rights to control who can edit attribute definitions, and who can edit the values of attribute definitions.
For example, you might want an attribute to generate history so that you can track changes to it. You set access controls on the attribute definition so that no one can turn the generate history option off. You might also want to allow only certain people edit the value of the attribute in the module. You set access controls for the attribute value so that only specific users can edit the value.
If you want to edit the URI and you are integrating with Rational® Insight, you must use a supported, predefined URI. For information about predefined URIs, see Predefined URIs for attributes in modules.