this class manages messages in a collaboration diagram
Declaration :
Directly inherited by : UmlCollaborationMessage
Artifact : UmlBaseCollaborationMessage
| Operation rank | 
return the global rank of the message
Declaration :
| Operation hrank | 
return the hierarchical rank of the message
Declaration :
| Attribute _rank | 
Declaration :
| Attribute _hrank | 
Declaration :
| Operation read_ | 
internal, don't call it
Declaration :
| Extra Class Member friend | 
Definition :
friend class UmlBaseCollaborationDiagramDefinition;
All public operations : form , from , hrank , operation , rank , read_ , read_ , to