DAV:activity-set

Is there any way to determine the set of activities for a working
resource as was specified in a preceding CHECKOUT?  Probably, somewhere
in section 13, there should be a DAV:activity-set defined for working
resources.  And in section 13.9, there should be a DAV:checkout-set
property (as in section 5.1.4) defined on activity resources, right?

Bye,
    Juergen