diff --git a/src/devices/wifi/wifi-net-device.cc b/src/devices/wifi/wifi-net-device.cc
index 2dfd04666..93be90727 100644
--- a/src/devices/wifi/wifi-net-device.cc
+++ b/src/devices/wifi/wifi-net-device.cc
@@ -38,29 +38,29 @@ WifiNetDevice::GetTypeId (void)
 {
   static TypeId tid = TypeId ("ns3::WifiNetDevice")
     .SetParent<NetDevice> ()
-    .AddAttribute ("Channel", "XXX",
+    .AddAttribute ("Channel", "The channel attached to this device",
                    Pointer (),
                    MakePointerAccessor (&WifiNetDevice::DoGetChannel,
                                         &WifiNetDevice::SetChannel),
                    MakePointerChecker<WifiChannel> ())
-    .AddAttribute ("Phy", "XXX",
+    .AddAttribute ("Phy", "The PHY layer attached to this device.",
                    Pointer (),
                    MakePointerAccessor (&WifiNetDevice::GetPhy,
                                         &WifiNetDevice::SetPhy),
                    MakePointerChecker<WifiPhy> ())
-    .AddAttribute ("Mac", "XXX",
+    .AddAttribute ("Mac", "The MAC layer attached to this device.",
                    Pointer (),
                    MakePointerAccessor (&WifiNetDevice::GetMac,
                                         &WifiNetDevice::SetMac),
                    MakePointerChecker<WifiMac> ())
-    .AddAttribute ("RemoteStationManager", "XXX",
+    .AddAttribute ("RemoteStationManager", "The station manager attached to this device.",
                    Pointer (),
                    MakePointerAccessor (&WifiNetDevice::SetRemoteStationManager,
                                         &WifiNetDevice::GetRemoteStationManager),
                    MakePointerChecker<WifiRemoteStationManager> ())
-    .AddTraceSource ("Rx", "XXX",
+    .AddTraceSource ("Rx", "Received payload from the MAC layer.",
                      MakeTraceSourceAccessor (&WifiNetDevice::m_rxLogger))
-    .AddTraceSource ("Tx", "XXX",
+    .AddTraceSource ("Tx", "Send payload to the MAC layer.",
                      MakeTraceSourceAccessor (&WifiNetDevice::m_txLogger))
     ;
   return tid;
diff --git a/src/internet-node/ipv4-l3-protocol.h b/src/internet-node/ipv4-l3-protocol.h
index b869d1f2d..969dc09ca 100644
--- a/src/internet-node/ipv4-l3-protocol.h
+++ b/src/internet-node/ipv4-l3-protocol.h
@@ -41,6 +41,9 @@ class Ipv4Route;
 class Node;
 
 
+/**
+ * \brief Implement the Ipv4 layer.
+ */
 class Ipv4L3Protocol : public Object
 {
 public:
diff --git a/src/node/queue.cc b/src/node/queue.cc
index 5b1852d8b..8021dc400 100644
--- a/src/node/queue.cc
+++ b/src/node/queue.cc
@@ -31,11 +31,11 @@ Queue::GetTypeId (void)
 {
   static TypeId tid = TypeId ("ns3::Queue")
     .SetParent<Object> ()
-    .AddTraceSource ("Enqueue", "XXX",
+    .AddTraceSource ("Enqueue", "Enqueue a packet in the queue.",
                      MakeTraceSourceAccessor (&Queue::m_traceEnqueue))
-    .AddTraceSource ("Dequeue", "XXX",
+    .AddTraceSource ("Dequeue", "Dequeue a packet from the queue.",
                      MakeTraceSourceAccessor (&Queue::m_traceDequeue))
-    .AddTraceSource ("Drop", "XXX",
+    .AddTraceSource ("Drop", "Drop a packet stored in the queue.",
                      MakeTraceSourceAccessor (&Queue::m_traceDrop))
     ;
   return tid;