--- a/src/common/tag.h	Tue May 06 14:54:44 2008 -0700
+++ b/src/common/tag.h	Tue May 06 14:54:52 2008 -0700
@@ -7,13 +7,34 @@
 
 namespace ns3 {
 
+/**
+ * \brief tag a set of bytes in a packet
+ *
+ * New kinds of tags can be created by subclassing this base class.
+ */
 class Tag : public ObjectBase
 {
 public:
   static TypeId GetTypeId (void);
 
+  /**
+   * \returns the number of bytes required to serialize the data of the tag.
+   *
+   * This method is typically invoked by Packet::AddTag just prior to calling
+   * Tag::Serialize.
+   */
   virtual uint32_t GetSerializedSize (void) const = 0;
+  /**
+   * \param i the buffer to write data into.
+   *
+   * Write the content of the tag in the provided tag buffer.
+   */
   virtual void Serialize (TagBuffer i) const = 0;
+  /**
+   * \param i the buffer to read data from.
+   *
+   * Read the content of the tag from the provided tag buffer.
+   */
   virtual void Deserialize (TagBuffer i) = 0;
 };