Catalog classes are created to be owned by dba. However, dba can only execute SELECT operations. If dba executes operations such as UPDATE/DELETE, an authorization failure error occurs. General users cannot execute queries on system catalog classes.
Although catalog virtual classes are created to be owned by dba, all users can perform the SELECT statement on catalog virtual classes. Of course, UPDATE/DELETE operations on catalog virtual classes are not allowed.
Updating catalog classes/virtual classes is automatically performed by the system when users execute a DDL statement that creates/modifies/deletes a class/attribute/index/user/authorization.