Last week I was at the OMG meeting in Salt Lake City. A high point of the meeting was issuing a Request for Proposals for a new “metamodel extension facility”, which could in time replace the current UML profile capability with a better designed and more flexible mechanism.  The new capability should allow the profile writer to select a subset of UML, including the possibility of choosing particular properties from a metaclass, and define a profile as a new metamodel that extends that subset.  So, if the profile writer wants to define Class without the properties “visibility” and “isActive” they will be able to do so.  They should also be able to define new notations for UML, if they want, although this is obviously a feature that needs to be used sensibly.