UML14 — UML 1.4: ClassifierRole contents problem

The UML 1.4 standard states [UML 1.4, pp. 2-121] that a ClassifierRole
"...specifies a restricted view of a [base] classifier.." and defines "...a
set of Features, which is a subset of those available in the base
classifier, as well as a subset of ModelElements contained in the base
classifier...".

The ClassifierRole wellformedness rules [UML 1.4, pp. 2-125] states that the
"feature" association inherited from Classifier must be empty - instead the
ClassifierRole must select features from the base classifier using the
"availableFeature" association [UML 1.4, pp. 2-121].

The ClassifierRole also has an "availableContents" association [UML 1.4, pp.
2-121] indicating "the subset of ModelElements contained in the base
Classifier, which is used in the Collaboration". There is however no
restriction in the wellformedness rules restricting the ownedElements
contents of the ClassifierRole itself, meaning that a ClassifierRole can
contain the following meta-elements:

Method
Attribute
Operation
Reception
State
ActionState
ObjectFlowState
Transition
CallState
Pseudostate
SimpleState
SubactivityState
SynchState
CompositeState
SubmachineState
SubState
FinalState
CallAction
TerminateAction
CreateAction
DestroyAction
SendAction
ActionSequence
UninterpretedAction
ReturnAction
ExtensionPoint
Stimulus
Parameter
Permission
UseCase
ProgrammingLanguageDataType
StateMachine
Comment
LinkObject
Enumeration
Association
Dependency
ClassifierInState
SignalEvent
Constraint
NodeInstance
Usage
Signal
Actor
Interface
Component
Link
Primitive
Collaboration
SubsystemInstance
ChangeEvent
Generalization
Stereotype
Subsystem
TagDefinition
Abstraction
Extend
ActivityGraph
Flow
UseCaseInstance
DataType
Object
Class
TimeEvent
ComponentInstance
Exception
Include
CollaborationInstanceSet
AssociationClass
CallEvent
Binding
Package
Node
Artifact
Model
DataValue
TaggedValue

So the question is: is this lack of restriction intentional? And if so, why
are ownedElements handled differently from features? And what is the
semantic difference between entities selected using the "availableContents"
association and those contained directly?

No Data Available