Here are some UML diagrams of the relationships in Libsigc++:

Scopes, Handles, Objects:   
------------------------     
                           
                     _________    scope_    _____________
                    |  Scope  |*<-------<> | Object_Impl |   
                    |         |    obj_    |             |
                    |_________|----------> |             |
                         A        (obj)    |             |
                         |          +----> |             |
                         |          |      |_____________|
                         |          |            A 
                     __________     |            |
 ________    scope_ |  Limit   |<>--+            *
|Handle  |<*>------>|          |            _____________
| <Limit>|          |__________|           | Object      |
|        |                                 |             |
|        |            (obj)                |             |  
|        |   (<>----------------------->)  |             |
|________|                                 |_____________|


Okay here is what you are supposed to get out of this.
Object comes from Object_Impl with multiplicity (VI).
Handle<Limit> in this case forms a virtual aggregate relationship
with the Object it points to.  

For future diagrams I would reduce this to
  
   Handle<Limit> <>--------> Object

Other handle relationships are formed with different types of
scopes.  Reference Count for example would have the same
diagram (but very different behavior.)

There is also a relation when the pointed to
object deletes itself when the object is removed.  This is
a dependency that will be written as

    A -----><> B

  
BasicSignal:
-----------

                ____________________     incoming_
               | BasicSignal_::InOut| <>----------->* Slot
               |                    | 
               |                    |    outgoing_ 
               |____________________| <>----------->* Slot
                            A
                            |
                            |
                ---------------------
               | BasicSignal#        |
               |                     |
               |_____________________|

It is clear from here that a BasicSignal is formed from a number of different
objects.


Connections between a BasicSignal and a Object method:

                         ----------                  ________
                        | SlotData |                | Object |
                        |__________|                |________|
                              A                         A
                              |                         |
                              |                         |
  ___________              _____________                |
 |BasicSignal| outgoing_  | ObjectSlot# |           ----------
 |___________|<>-------->*|             |          | MyObject | 
                          |             |-------><>|          |
  ___________             |             |          |__________|
 |Connection |----------> |_____________|
 |___________|