Clarify pkt-uid field in doxygen

examples/wscript

@@ -18,6 +18,10 @@ def build(bld):
         ['csma', 'internet-node'])
     obj.source = 'csma-one-subnet.cc'
 
+    obj = bld.create_ns3_program('george',
+        ['csma', 'internet-node'])
+    obj.source = 'george.cc'
+
     obj = bld.create_ns3_program('udp-echo',
         ['csma', 'internet-node'])
     obj.source = 'udp-echo.cc'

src/common/packet.h

@@ -243,6 +243,16 @@ public:
   /**
    * A packet is allocated a new uid when it is created
    * empty or with zero-filled payload.
+   * 
+   * Note:  This uid is an internal uid and cannot be counted on to 
+   * provide an accurate counter of how many "simulated packets" of a 
+   * particular protocol are in the system.  It is not trivial to make
+   * this uid into such a counter, because of questions such as what
+   * should the uid be when the packet is sent over broadcast media, or
+   * when fragmentation occurs.  If a user wants to trace actual packet
+   * counts, he or she should look at e.g. the IP ID field or transport
+   * sequence numbers, or other packet or frame counters at other 
+   * protocol layers.
    *
    * \returns an integer identifier which uniquely
    *          identifies this packet.

src/core/object.cc

@@ -197,6 +197,7 @@ Object::DoQueryInterface (InterfaceId iid) const
   do {
     NS_ASSERT (currentObject != 0);
     InterfaceId cur = currentObject->m_iid;
+    NS_LOG_LOGIC("In Loop: " << cur.GetName());
     while (cur != iid && cur != Object::iid)
       {
         cur = InterfaceId::LookupParent (cur);