Extensibility for all DeltaV methods

DeltaV methods which take request bodies are extensible, in that the DTDs
for the top-level element in the body are all declared to allow ANY
sub-elements. However, there are three methods which are not defined to take
request bodies: MKACTIVITY, MKWORKSPACE, and UNCHECKOUT. Should the protocol
explicitly declare that they can be extended by defining request bodies for
them?

John