improve comments
diff --git a/include/FLAC++/all.h b/include/FLAC++/all.h
index b03612c..ca9efe6 100644
--- a/include/FLAC++/all.h
+++ b/include/FLAC++/all.h
@@ -43,11 +43,6 @@
  * The FLAC C++ API is the interface to libFLAC++, a set of classes
  * that encapsulate the encoders, decoders, and metadata interfaces
  * in libFLAC.
- *
- * Note that Doxygen currently has some quirks (bugs?) in the way
- * it deals with some member groups and C++ constructs.  You will find
- * some document entries in the wrong place under [NOHEADER] sections.
- * Hopefully this is not too distracting.
  */
 
 #endif
diff --git a/include/FLAC++/decoder.h b/include/FLAC++/decoder.h
index 8537f99..9d18ed7 100644
--- a/include/FLAC++/decoder.h
+++ b/include/FLAC++/decoder.h
@@ -66,37 +66,29 @@
  * property.
  *
  * Second, there are two stream decoder classes.  FLAC::Decoder::Stream
- * is used for the same cases that FLAC__stream_decoder_init_stream() is
- * used, and FLAC::Decoder::File is used for the same cases that
- * FLAC__stream_decoder_init_FILE() and FLAC__stream_decoder_init_file()
+ * is used for the same cases that FLAC__stream_decoder_init_stream() /
+ * FLAC__stream_decoder_init_ogg_stream() is used, and FLAC::Decoder::File
+ * is used for the same cases that
+ * FLAC__stream_decoder_init_FILE() and FLAC__stream_decoder_init_file() /
+ * FLAC__stream_decoder_init_ogg_FILE() and FLAC__stream_decoder_init_ogg_file()
  * are used.
  */
 
 namespace FLAC {
 	namespace Decoder {
 
-		/** \defgroup flacpp_stream_decoder FLAC++/decoder.h: stream decoder class
-		 *  \ingroup flacpp_decoder
-		 *
+		/** \ingroup flacpp_decoder
 		 *  \brief
-		 *  This class wraps the ::FLAC__StreamDecoder.
-		 *
-		 * See the \link flac_stream_decoder libFLAC stream decoder module \endlink
-		 * for basic usage.
-		 *
-		 * \{
-		 */
-
-		/** This class wraps the ::FLAC__StreamDecoder.  If you are
+		 *  This class wraps the ::FLAC__StreamDecoder.  If you are
 		 *  decoding from a file, FLAC::Decoder::File may be more
 		 *  convenient.
 		 *
 		 * The usage of this class is similar to FLAC__StreamDecoder,
 		 * except instead of providing callbacks to
-		 * FLAC__stream_decoder_init_stream(), you will inherit from this
+		 * FLAC__stream_decoder_init*_stream(), you will inherit from this
 		 * class and override the virtual callback functions with your
-		 * own implementations, then call Stream::init().  The rest of
-		 * the calls work the same as in the C layer.
+		 * own implementations, then call init() or init_ogg().  The rest
+		 * of the calls work the same as in the C layer.
 		 *
 		 * Only the read, write, and error callbacks are mandatory.  The
 		 * others are optional; this class provides default
@@ -126,7 +118,7 @@
 			 *  successfully.  If not, use get_state() to find out why not.
 			 */
 			virtual bool is_valid() const;
-			inline operator bool() const { return is_valid(); }
+			inline operator bool() const { return is_valid(); } ///< See is_valid()
 			//@}
 
 			virtual bool set_ogg_serial_number(long value);                        ///< See FLAC__stream_decoder_set_ogg_serial_number()
@@ -210,31 +202,19 @@
 			void operator=(const Stream &);
 		};
 
-		/* \} */
-
-		/** \defgroup flacpp_file_decoder FLAC++/decoder.h: file decoder class
-		 *  \ingroup flacpp_decoder
-		 *
+		/** \ingroup flacpp_decoder
 		 *  \brief
-		 *  This class wraps the ::FLAC__StreamDecoder.
-		 *
-		 * See the \link flac_stream_decoder libFLAC stream decoder module \endlink
-		 * for basic usage.
-		 *
-		 * \{
-		 */
-
-		/** This class wraps the ::FLAC__StreamDecoder.  If you are
+		 *  This class wraps the ::FLAC__StreamDecoder.  If you are
 		 *  not decoding from a file, you may need to use
 		 *  FLAC::Decoder::Stream.
 		 *
 		 * The usage of this class is similar to FLAC__StreamDecoder,
 		 * except instead of providing callbacks to
-		 * FLAC__stream_decoder_init_FILE() or
-		 * FLAC__stream_decoder_init_file(), you will inherit from this
+		 * FLAC__stream_decoder_init*_FILE() or
+		 * FLAC__stream_decoder_init*_file(), you will inherit from this
 		 * class and override the virtual callback functions with your
-		 * own implementations, then call File::init().  The rest of
-		 * the calls work the same as in the C layer.
+		 * own implementations, then call init() or init_off().  The rest
+		 * of the calls work the same as in the C layer.
 		 *
 		 * Only the write, and error callbacks from FLAC::Decoder::Stream
 		 * are mandatory.  The others are optional; this class provides
@@ -261,8 +241,6 @@
 			void operator=(const File &);
 		};
 
-		/* \} */
-
 	}
 }
 
diff --git a/include/FLAC++/encoder.h b/include/FLAC++/encoder.h
index d506dc1..b974cc4 100644
--- a/include/FLAC++/encoder.h
+++ b/include/FLAC++/encoder.h
@@ -67,36 +67,28 @@
  * property.
  *
  * Second, there are two stream encoder classes.  FLAC::Encoder::Stream
- * is used for the same cases that FLAC__stream_encoder_init_stream() is
- * used, and FLAC::Encoder::File is used for the same cases that
- * FLAC__stream_encoder_init_FILE() and FLAC__stream_encoder_init_file()
+ * is used for the same cases that FLAC__stream_encoder_init_stream() /
+ * FLAC__stream_encoder_init_ogg_stream() is used, and FLAC::Encoder::File
+ * is used for the same cases that
+ * FLAC__stream_encoder_init_FILE() and FLAC__stream_encoder_init_file() /
+ * FLAC__stream_encoder_init_ogg_FILE() and FLAC__stream_encoder_init_ogg_file()
  * are used.
  */
 
 namespace FLAC {
 	namespace Encoder {
 
-		/** \defgroup flacpp_stream_encoder FLAC++/encoder.h: stream encoder class
-		 *  \ingroup flacpp_encoder
-		 *
+		/** \ingroup flacpp_encoder
 		 *  \brief
-		 *  This class wraps the ::FLAC__StreamEncoder.
-		 *
-		 * See the \link flac_stream_encoder libFLAC stream encoder module \endlink
-		 * for basic usage.
-		 *
-		 * \{
-		 */
-
-		/** This class wraps the ::FLAC__StreamEncoder.  If you are
+		 *  This class wraps the ::FLAC__StreamEncoder.  If you are
 		 *  encoding to a file, FLAC::Encoder::File may be more
 		 *  convenient.
 		 *
 		 * The usage of this class is similar to FLAC__StreamEncoder,
 		 * except instead of providing callbacks to
-		 * FLAC__stream_encoder_init_stream(), you will inherit from this
+		 * FLAC__stream_encoder_init*_stream(), you will inherit from this
 		 * class and override the virtual callback functions with your
-		 * own implementations, then call Stream::init().  The rest of
+		 * own implementations, then call init() or init_ogg().  The rest of
 		 * the calls work the same as in the C layer.
 		 *
 		 * Only the write callback is mandatory.  The others are
@@ -129,7 +121,7 @@
 			 *
 			 */
 			virtual bool is_valid() const;
-			inline operator bool() const { return is_valid(); }
+			inline operator bool() const { return is_valid(); } ///< See is_valid()
 			//@}
 
 			virtual bool set_ogg_serial_number(long value);                 ///< See FLAC__stream_encoder_set_ogg_serial_number()
@@ -219,31 +211,19 @@
 			void operator=(const Stream &);
 		};
 
-		/* \} */
-
-		/** \defgroup flacpp_file_encoder FLAC++/encoder.h: file encoder class
-		 *  \ingroup flacpp_encoder
-		 *
+		/** \ingroup flacpp_encoder
 		 *  \brief
-		 *  This class wraps the ::FLAC__StreamEncoder.
-		 *
-		 * See the \link flac_stream_encoder libFLAC stream encoder module \endlink
-		 * for basic usage.
-		 *
-		 * \{
-		 */
-
-		/** This class wraps the ::FLAC__StreamEncoder.  If you are
+		 *  This class wraps the ::FLAC__StreamEncoder.  If you are
 		 *  not encoding to a file, you may need to use
 		 *  FLAC::Encoder::Stream.
 		 *
 		 * The usage of this class is similar to FLAC__StreamEncoder,
 		 * except instead of providing callbacks to
-		 * FLAC__stream_encoder_init_FILE() or
-		 * FLAC__stream_encoder_init_file(), you will inherit from this
+		 * FLAC__stream_encoder_init*_FILE() or
+		 * FLAC__stream_encoder_init*_file(), you will inherit from this
 		 * class and override the virtual callback functions with your
-		 * own implementations, then call File::init().  The rest of
-		 * the calls work the same as in the C layer.
+		 * own implementations, then call init() or init_ogg().  The rest
+		 * of the calls work the same as in the C layer.
 		 *
 		 * There are no mandatory callbacks; all the callbacks from
 		 * FLAC::Encoder::Stream are implemented here fully and support
diff --git a/include/FLAC++/metadata.h b/include/FLAC++/metadata.h
index 1f8b7ba..9962314 100644
--- a/include/FLAC++/metadata.h
+++ b/include/FLAC++/metadata.h
@@ -64,7 +64,8 @@
  *
  *  The behavior closely mimics the C layer interface; be sure to read
  *  the detailed description of the
- *  \link flac_metadata C metadata module \endlink.
+ *  \link flac_metadata C metadata module \endlink.  Note that the
+ *  metadata API currently does not support Ogg FLAC files.
  */
 
 
@@ -563,7 +564,7 @@
 
 				virtual ~Entry();
 
-				virtual bool is_valid() const;
+				virtual bool is_valid() const; ///< Returns \c true iff object was properly constructed.
 
 				unsigned get_field_length() const;
 				unsigned get_field_name_length() const;
@@ -687,7 +688,8 @@
 
 				virtual ~Track();
 
-				virtual bool is_valid() const;
+				virtual bool is_valid() const; ///< Returns \c true iff object was properly constructed.
+
 
 				inline FLAC__uint64 get_offset() const { return object_->offset; }
 				inline FLAC__byte get_number() const { return object_->number; }
@@ -1005,9 +1007,10 @@
 			SimpleIterator();
 			virtual ~SimpleIterator();
 
+			bool is_valid() const; ///< Returns \c true iff object was properly constructed.
+
 			bool init(const char *filename, bool read_only, bool preserve_file_stats); ///< See FLAC__metadata_simple_iterator_init().
 
-			bool is_valid() const;
 			Status status();                                                    ///< See FLAC__metadata_simple_iterator_status().
 			bool is_writable() const;                                           ///< See FLAC__metadata_simple_iterator_is_writable().
 
@@ -1088,7 +1091,8 @@
 
 			friend class Iterator;
 
-			bool is_valid() const;
+			bool is_valid() const; ///< Returns \c true iff object was properly constructed.
+
 			Status status();                                                ///< See FLAC__metadata_chain_status().
 
 			bool read(const char *filename);                                ///< See FLAC__metadata_chain_read().
@@ -1118,7 +1122,8 @@
 			Iterator();
 			virtual ~Iterator();
 
-			bool is_valid() const;
+			bool is_valid() const; ///< Returns \c true iff object was properly constructed.
+
 
 			void init(Chain &chain);                       ///< See FLAC__metadata_iterator_init().