Comment 1 for bug 153333

Existing content classes and database classes needs to be audited for their use of the "registrant" and "owner" attributes.

 * Where "owner" is used and "registrant" should be used, the attribute should be renamed.
 * Where ownership semantics are wanted, but an immutable "registrant" attribute is used, a mutable "owner" attribute should be added, initially set to the registrant.
 * Where no immutable attribute is present to record the person who registered the object, a "registrant" attribute should be added. A data migration strategy (picking a default value, or allowing NULL values) must be defined.