'InstanceID is an optional property that may be used to opaquely and uniquely identify an instance of this class within the scope of the instantiating Namespace. Various subclasses of this class may override this property to make it required, or a key. Such subclasses may also modify the preferred algorithms for ensuring uniqueness that are defined below. To ensure uniqueness within the NameSpace, the value of InstanceID should be constructed using the following "preferred" algorithm: : Where and are separated by a colon (:), and where must include a copyrighted, trademarked, or otherwise unique name that is owned by the business entity that is creating or defining the InstanceID or that is a registered ID assigned to the business entity by a recognized global authority. (This requirement is similar to the _ structure of Schema class names.) In addition, to ensure uniqueness, must not contain a colon (:). When using this algorithm, the first colon to appear in InstanceID must appear between and . is chosen by the business entity and should not be reused to identify different underlying (real-world) elements. If not null and the above "preferred" algorithm is not used, the defining entity must assure that the resulting InstanceID is not reused across any InstanceIDs produced by this or other providers for the NameSpace of this instance. If not set to null for DMTF-defined instances, the "preferred" algorithm must be used with the set to CIM.'