diff --git a/src/common/header.h b/src/common/header.h
index e82ae1c16..39ff037c6 100644
--- a/src/common/header.h
+++ b/src/common/header.h
@@ -63,20 +63,24 @@ namespace ns3 {
  *
  * Each header must also make sure that:
  *   - it defines a public default constructor
- *   - it defines a public static method named GetUid which returns a string.
+ *   - it defines a public static method named GetUid which returns a 32 bit integer
  *
- * The latter should look like the following to ensure that
- * every header returns a unique string.
+ * The latter should look like the following:
  * \code
+ * // in the header,
  * class MyHeader : public Header
  * {
  * public:
- *   static const char *GetUid (void);
+ *   static uint32_t GetUid (void);
  * };
  *
- * const char *MyHeader::GetUid (void)
+ * // in the source file:
+ * NS_HEADER_ENSURE_REGISTERED (MyHeader);
+ *
+ * uint32_t MyHeader::GetUid (void)
  * {
- *   return "MyHeader.unique.prefix";
+ *   static uint32_t uid = Header::Register<MyHeader> ("MyHeader.unique.prefix");
+ *   return uid;
  * }
  * \endcode
  *
diff --git a/src/common/packet.h b/src/common/packet.h
index f4b0af11d..ce614d2c6 100644
--- a/src/common/packet.h
+++ b/src/common/packet.h
@@ -327,6 +327,7 @@ private:
  *
  * So, a tag class should look like this:
  * \code
+ * // in header file
  * // note how a tag class does not derive from any other class.
  * class MyTag 
  * {
@@ -334,9 +335,9 @@ private:
  *   // we need a public default constructor
  *   MyTag ();
  *   // we need a public static GetUid
- *   // GetUid must return a string which uniquely
+ *   // GetUid must return a 32 bit integer which uniquely
  *   // identifies this tag type
- *   static std::string GetUid (void);
+ *   static uint32_t GetUid (void);
  *   // Print should record in the output stream
  *   // the content of the tag instance.
  *   void Print (std::ostream &os) const;
@@ -352,11 +353,16 @@ private:
  *   uint32_t Deserialize (Buffer::Iterator i);
  * };
  *
+ * // in source file
+ * 
+ * NS_TAG_ENSURE_REGISTERED (MyTag);
+ *
  * std::string MyTag::GetUid (void)
  * {
  *   // we really want to make sure that this
  *   // string is unique in the universe.
- *   return "MyTag.unique.prefix";
+ *   static uint32_t uid = TagRegistry<MyTag> ("MyTag.unique.prefix");
+ *   return uid;
  * }
  * \endcode
  */
diff --git a/src/common/trailer.h b/src/common/trailer.h
index 6184f8a5f..b7a306a17 100644
--- a/src/common/trailer.h
+++ b/src/common/trailer.h
@@ -63,20 +63,24 @@ namespace ns3 {
  *
  * Each trailer must also make sure that:
  *   - it defines a public default constructor
- *   - it defines a public static method named GetUid which returns a string.
+ *   - it defines a public static method named GetUid which returns a 32 bit integer.
  *
- * The latter should look like the following to ensure that
- * every trailer returns a unique string.
+ * The latter should look like the following:
  * \code
+ * // in the header
  * class MyTrailer : public Header
  * {
  * public:
- *   static const char *GetUid (void);
+ *   static uint32_t GetUid (void);
  * };
  *
- * const char *MyTrailer::GetUid (void)
+ * // in the source file
+ * NS_TRAILER_ENSURE_REGISTERED (MyTrailer);
+ *
+ * uint32_t MyTrailer::GetUid (void)
  * {
- *   return "MyTrailer.unique.prefix";
+ *   static uint32_t uid = Trailer::Register<MyTrailer> ("MyTrailer.unique.prefix");
+ *   return uid;
  * }
  * \endcode
  *