this class manages use case references
Declaration :
Directly inherited by : UmlUseCaseReference
Artifact : UmlBaseUseCaseReference
| Operation useCase | 
return the use case
Declaration :
| Operation fragment | 
return the fragment compartment containing the
 use case, or 0/null
Declaration :
| Operation subject | 
return the subject containing the use case, or 0/null
Declaration :
| Relation _use_case (<unidirectional association>) | 
Declaration :
| Relation _fragment (<unidirectional association>) | 
Declaration :
| Relation _subject (<unidirectional association>) | 
Declaration :
| Attribute _x | 
Declaration :
| Attribute _y | 
Declaration :
| Attribute _w | 
Declaration :
| Attribute _h | 
Declaration :
| Operation read_ | 
internal, don't call it
Declaration :
| Extra Class Member friend | 
Definition :
friend class UmlBaseUseCaseDiagramDefinition;
All public operations : fragment , read_ , subject , useCase