diff --git a/MidiPlayer.Droid/MainActivity.Component.cs b/MidiPlayer.Droid/MainActivity.Component.cs
index 08fef30..06e8f0e 100644
--- a/MidiPlayer.Droid/MainActivity.Component.cs
+++ b/MidiPlayer.Droid/MainActivity.Component.cs
@@ -9,7 +9,7 @@ namespace MidiPlayer.Droid {
     public partial class MainActivity : AppCompatActivity {
 
         ///////////////////////////////////////////////////////////////////////////////////////////////
-        // private Methods [verb]
+        // private Methods [verb, verb phrases]
 
         /// <summary>
         /// initialize the component.
diff --git a/MidiPlayer.Droid/MainActivity.cs b/MidiPlayer.Droid/MainActivity.cs
index ecfc158..685954b 100644
--- a/MidiPlayer.Droid/MainActivity.cs
+++ b/MidiPlayer.Droid/MainActivity.cs
@@ -21,7 +21,7 @@ namespace MidiPlayer.Droid {
     public partial class MainActivity : AppCompatActivity {
 
         ///////////////////////////////////////////////////////////////////////////////////////////////
-        // Fields
+        // Fields [nouns, noun phrases]
 
         string soundFontPath = "undefined";
 
@@ -54,22 +54,19 @@ protected override void OnCreate(Bundle savedInstanceState) {
             initializeComponent();
             Conf.Load();
 
-            int _count = 0;
-            Synth.OnMessage += (IntPtr data, IntPtr evt) => {
-                //Log.Info($"OnMessage count: {_count}");
-                _count++;
+            Synth.Playbacking += (IntPtr data, IntPtr evt) => {
                 return Synth.HandleEvent(data, evt);
             };
 
-            Synth.OnStart += () => {
-                Log.Info("OnStart called.");
+            Synth.Started += () => {
+                Log.Info("Started called.");
                 MainThread.BeginInvokeOnMainThread(() => {
                     Title = $"MidiPlayer: {Synth.MidiFilePath.ToFileName()} {Synth.SoundFontPath.ToFileName()}";
                 });
             };
 
-            Synth.OnEnd += () => {
-                Log.Info("OnEnd called.");
+            Synth.Ended += () => {
+                Log.Info("Ended called.");
                 if (!playList.Ready) {
                     Synth.Stop();
                     Synth.Start();
@@ -436,7 +433,7 @@ void buttonSendSynth_16_Click(object sender, EventArgs e) {
         }
 
         ///////////////////////////////////////////////////////////////////////////////////////////////
-        // private Methods [verb]
+        // private Methods [verb, verb phrases]
 
         void requestPermissions() {
             if (ContextCompat.CheckSelfPermission(this, Manifest.Permission.ReadExternalStorage) != (int) Permission.Granted) {
diff --git a/MidiPlayer.FluidSynth/Synth.cs b/MidiPlayer.FluidSynth/Synth.cs
index 0461dba..de46b37 100644
--- a/MidiPlayer.FluidSynth/Synth.cs
+++ b/MidiPlayer.FluidSynth/Synth.cs
@@ -20,7 +20,7 @@ namespace MidiPlayer {
     public class Synth {
 
         ///////////////////////////////////////////////////////////////////////////////////////////////
-        // static Fields
+        // static Fields [nouns, noun phrases]
 
         static fluid_settings_t setting = IntPtr.Zero;
 
@@ -32,13 +32,13 @@ public class Synth {
 
         static handle_midi_event_func_t event_callback;
 
-        static Func<IntPtr, IntPtr, int> onMessage;
+        static Func<IntPtr, IntPtr, int> onPlaybacking;
 
-        static Action onStart;
+        static Action onStarted;
 
-        static Action onEnd;
+        static Action onEnded;
 
-        static Action<object, PropertyChangedEventArgs> onUpdate;
+        static Action<object, PropertyChangedEventArgs> onUpdated;
 
         static string soundFontPath;
 
@@ -56,7 +56,7 @@ public class Synth {
         // static Constructor
 
         static Synth() {
-            onMessage += (void_ptr data, fluid_midi_event_t evt) => {
+            onPlaybacking += (void_ptr data, fluid_midi_event_t evt) => {
                 Enumerable.Range(0, 16).ToList().ForEach(x => {
                     var _data = EventQueue.Dequeue(x);
                     if (!(_data is null)) {
@@ -89,7 +89,7 @@ static Synth() {
         }
 
         ///////////////////////////////////////////////////////////////////////////////////////////////
-        // static Properties [noun, adjective] 
+        // static Properties [noun, noun phrase, adjective] 
 
         public static string SoundFontPath {
             get => soundFontPath;
@@ -120,33 +120,33 @@ public static bool Playing {
         }
 
         ///////////////////////////////////////////////////////////////////////////////////////////////
-        // static Events [adjective] 
+        // static Events [verb, verb phrase] 
 
-        public static event Func<IntPtr, IntPtr, int> OnMessage {
+        public static event Func<IntPtr, IntPtr, int> Playbacking {
             add {
-                onMessage += value;
-                event_callback = new handle_midi_event_func_t(onMessage);
+                onPlaybacking += value;
+                event_callback = new handle_midi_event_func_t(onPlaybacking);
             }
-            remove => onMessage -= value;
+            remove => onPlaybacking -= value;
         }
 
-        public static event Action OnStart {
-            add => onStart += value;
-            remove => onStart -= value;
+        public static event Action Started {
+            add => onStarted += value;
+            remove => onStarted -= value;
         }
 
-        public static event Action OnEnd {
-            add => onEnd += value;
-            remove => onEnd -= value;
+        public static event Action Ended {
+            add => onEnded += value;
+            remove => onEnded -= value;
         }
 
-        public static event Action<object, PropertyChangedEventArgs> OnUpdate {
-            add => onUpdate += value;
-            remove => onUpdate -= value;
+        public static event Action<object, PropertyChangedEventArgs> Updated {
+            add => onUpdated += value;
+            remove => onUpdated -= value;
         }
 
         ///////////////////////////////////////////////////////////////////////////////////////////////
-        // public static Methods [verb]
+        // public static Methods [verb, verb phrases]
 
         public static void Init() {
             try {
@@ -177,7 +177,7 @@ public static void Init() {
                 }
                 Multi.StandardMidiFile = standardMidiFile;
                 Enumerable.Range(0, 16).ToList().ForEach(x => {
-                    Multi.Get(x).PropertyChanged += onUpdateCallBack;
+                    Multi.Get(x).PropertyChanged += onPropertyChanged;
                 });
                 int _result = fluid_player_add(player, MidiFilePath);
                 if (_result == FLUID_FAILED) {
@@ -205,11 +205,11 @@ public static void Start() {
                 adriver = new_fluid_audio_driver(setting, synth);
                 fluid_player_play(player);
                 Log.Info("start :)");
-                onStart();
+                onStarted();
                 fluid_player_join(player);
                 Log.Info("end :D");
                 if (stopping == false) {
-                    onEnd();
+                    onEnded();
                 }
             } catch (Exception ex) {
                 Log.Error(ex.Message);
@@ -273,7 +273,7 @@ public static bool IsSounded(int channel) {
         }
 
         ///////////////////////////////////////////////////////////////////////////////////////////////
-        // private static Methods [verb]
+        // private static Methods [verb, verb phrases]
 
         static void final() {
             try {
@@ -294,8 +294,8 @@ static void final() {
             }
         }
 
-        static void onUpdateCallBack(object sender, PropertyChangedEventArgs e) {
-            onUpdate(sender, e);
+        static void onPropertyChanged(object sender, PropertyChangedEventArgs e) {
+            onUpdated(sender, e);
         }
 
         ///////////////////////////////////////////////////////////////////////////////////////////////
@@ -304,7 +304,7 @@ static void onUpdateCallBack(object sender, PropertyChangedEventArgs e) {
         static class Multi {
 
             ///////////////////////////////////////////////////////////////////////////////////////////
-            // static Fields
+            // static Fields [nouns, noun phrases]
 
             static Map<int, Track> trackMap;
 
@@ -318,7 +318,7 @@ static Multi() {
             }
 
             ///////////////////////////////////////////////////////////////////////////////////////////
-            // static Properties [noun, adjective]
+            // static Properties [noun, noun phrase, adjective]
 
             public static List<Track> List {
                 get => trackMap.Select(x => x.Value).ToList();
@@ -333,7 +333,7 @@ public static StandardMidiFile StandardMidiFile {
             }
 
             ///////////////////////////////////////////////////////////////////////////////////////////
-            // public static Methods [verb]
+            // public static Methods [verb, verb phrases]
 
             /// <summary>
             /// NOTE_ON = 144
@@ -394,7 +394,7 @@ public static Track Get(int track) {
             }
 
             ///////////////////////////////////////////////////////////////////////////////////////////
-            // private static Methods [verb]
+            // private static Methods [verb, verb phrases]
 
             static void init() {
                 trackMap.Clear();
@@ -411,7 +411,7 @@ static void init() {
         public class Track : INotifyPropertyChanged {
 
             ///////////////////////////////////////////////////////////////////////////////////////////
-            // Fields
+            // Fields [nouns, noun phrases]
 
             int index = -1;
 
@@ -433,7 +433,7 @@ public Track(int index) {
             }
 
             ///////////////////////////////////////////////////////////////////////////////////////////
-            // Events [adjective] 
+            // Events [verb, verb phrase] 
 
             /// <summary>
             /// implementation for INotifyPropertyChanged
@@ -441,7 +441,7 @@ public Track(int index) {
             public event PropertyChangedEventHandler PropertyChanged;
 
             ///////////////////////////////////////////////////////////////////////////////////////////
-            // Properties [noun, adjective]
+            // Properties [noun, noun phrase, adjective]
 
             public int Index {
                 get => index;
diff --git a/MidiPlayer.Midi/StandardMidiFile.cs b/MidiPlayer.Midi/StandardMidiFile.cs
index b29dd0a..cfecce0 100644
--- a/MidiPlayer.Midi/StandardMidiFile.cs
+++ b/MidiPlayer.Midi/StandardMidiFile.cs
@@ -11,7 +11,7 @@ namespace MidiPlayer.Midi {
     public class StandardMidiFile {
 
         ///////////////////////////////////////////////////////////////////////////////////////////////
-        // Fields
+        // Fields [nouns, noun phrases]
 
         Sequence sequence;
 
@@ -39,7 +39,7 @@ public StandardMidiFile(string target) {
         }
 
         ///////////////////////////////////////////////////////////////////////////////////////////////
-        // Properties [noun, adjective] 
+        // Properties [noun, noun phrase, adjective] 
 
         public int TrackCount {
             get => sequence.Count - 1; // exclude conductor track;
@@ -50,21 +50,21 @@ public List<int> MidiChannelList {
         }
 
         ///////////////////////////////////////////////////////////////////////////////////////////////
-        // public Methods [verb]
+        // public Methods [verb, verb phrases]
 
         public string GetTrackName(int track) {
             return nameAndMidiChannelMap[track].name;
         }
 
         ///////////////////////////////////////////////////////////////////////////////////////////////
-        // private Properties [noun, adjective] 
+        // private Properties [noun, noun phrase, adjective] 
 
         int trackCountIncludeConductorTrack {
             get => sequence.Count;
         }
 
         ///////////////////////////////////////////////////////////////////////////////////////////////
-        // private Methods [verb]
+        // private Methods [verb, verb phrases]
 
         string getTrackName(int track) {
             var _trackName = "undefined";
diff --git a/MidiPlayer.SoundFont/SoundFont .cs b/MidiPlayer.SoundFont/SoundFont .cs
index 6c28d7d..e56383c 100644
--- a/MidiPlayer.SoundFont/SoundFont .cs	
+++ b/MidiPlayer.SoundFont/SoundFont .cs	
@@ -10,7 +10,7 @@ namespace MidiPlayer.SoundFont {
     public class SoundFontInfo {
 
         ///////////////////////////////////////////////////////////////////////////////////////////////
-        // Fields
+        // Fields [nouns, noun phrases]
 
         NAudio.SoundFont.SoundFont soundFont;
 
@@ -42,7 +42,7 @@ public SoundFontInfo(string target) {
         }
 
         ///////////////////////////////////////////////////////////////////////////////////////////////
-        // public Methods [verb]
+        // public Methods [verb, verb phrases]
 
         public string GetVoice(int bank, int prog) {
             var _voice = map[bank];
@@ -60,7 +60,7 @@ public string GetVoice(int bank, int prog) {
         class Voice {
 
             ///////////////////////////////////////////////////////////////////////////////////////////
-            // Properties [noun, adjective] 
+            // Properties [noun, noun phrase, adjective] 
 
             public int Prog {
                 get; set;
diff --git a/MidiPlayer.Win64/BufferedListView.cs b/MidiPlayer.Win64/BufferedListView.cs
index 936a9b9..e4ff282 100644
--- a/MidiPlayer.Win64/BufferedListView.cs
+++ b/MidiPlayer.Win64/BufferedListView.cs
@@ -8,7 +8,7 @@ namespace MidiPlayer.Win64 {
     public class BufferedListView : ListView {
 
         ///////////////////////////////////////////////////////////////////////////////////////////////
-        // protected Methods [verb]
+        // protected Methods [verb, verb phrases]
 
         protected override bool DoubleBuffered {
             get {
diff --git a/MidiPlayer.Win64/MainForm.cs b/MidiPlayer.Win64/MainForm.cs
index f42cc89..f9bc456 100644
--- a/MidiPlayer.Win64/MainForm.cs
+++ b/MidiPlayer.Win64/MainForm.cs
@@ -13,7 +13,7 @@ namespace MidiPlayer.Win64 {
     public partial class MainForm : Form {
 
         ///////////////////////////////////////////////////////////////////////////////////////////////
-        // Fields
+        // Fields [nouns, noun phrases]
 
         string soundFontPath = "undefined";
 
@@ -37,12 +37,12 @@ void MainForm_Load(object sender, EventArgs e) {
             Conf.Load();
             initializeControl();
 
-            Synth.OnMessage += (IntPtr data, IntPtr evt) => {
+            Synth.Playbacking += (IntPtr data, IntPtr evt) => {
                 return Synth.HandleEvent(data, evt);
             };
 
-            Synth.OnStart += () => {
-                Log.Info("OnStart called.");
+            Synth.Started += () => {
+                Log.Info("Started called.");
                 Invoke((MethodInvoker) (() => {
                     Text = $"MidiPlayer: {Synth.MidiFilePath.ToFileName()} {Synth.SoundFontPath.ToFileName()}";
                     listView.Items.Clear();
@@ -52,8 +52,8 @@ void MainForm_Load(object sender, EventArgs e) {
                 }));
             };
 
-            Synth.OnEnd += () => {
-                Log.Info("OnEnd called.");
+            Synth.Ended += () => {
+                Log.Info("Ended called.");
                 if (!playList.Ready) {
                     Synth.Stop();
                     Synth.Start();
@@ -64,7 +64,7 @@ void MainForm_Load(object sender, EventArgs e) {
                 }
             };
 
-            Synth.OnUpdate += (object sender, PropertyChangedEventArgs e) => {
+            Synth.Updated += (object sender, PropertyChangedEventArgs e) => {
                 var _track = (Synth.Track) sender;
                 Invoke(updateList(_track));
             };
@@ -124,7 +124,7 @@ void buttonStop_Click(object sender, EventArgs e) {
         }
 
         ///////////////////////////////////////////////////////////////////////////////////////////////
-        // private Methods [verb]
+        // private Methods [verb, verb phrases]
 
         async void playSong() {
             try {
diff --git a/MidiPlayer/Conf.cs b/MidiPlayer/Conf.cs
index ee475b5..20c135c 100644
--- a/MidiPlayer/Conf.cs
+++ b/MidiPlayer/Conf.cs
@@ -11,14 +11,14 @@ namespace MidiPlayer {
     public class Conf {
 
         ///////////////////////////////////////////////////////////////////////////////////////////////
-        // static Fields
+        // static Fields [nouns, noun phrases]
 
         static readonly string APP_CONF_FILE_PATH = "storage/emulated/0/Android/data/com.studio.meowtoon.midiplayer/files/app_conf.json";
 
         static Json json = null;
 
         ///////////////////////////////////////////////////////////////////////////////////////////////
-        // static Properties [noun, adjective] 
+        // static Properties [noun, noun phrase, adjective] 
 
         public static bool Ready {
             get => !(json is null);
@@ -34,7 +34,7 @@ public static App Value {
         }
 
         ///////////////////////////////////////////////////////////////////////////////////////////////
-        // public static Methods [verb]
+        // public static Methods [verb, verb phrases]
 
         public static void Load() {
             if (File.Exists(APP_CONF_FILE_PATH)) {
@@ -60,7 +60,7 @@ public static void Save() {
         }
 
         ///////////////////////////////////////////////////////////////////////////////////////////////
-        // private static Methods [verb]
+        // private static Methods [verb, verb phrases]
 
         static Json loadJson(Stream target) {
             var _serializer = new DataContractJsonSerializer(typeof(Json));
diff --git a/MidiPlayer/Env.cs b/MidiPlayer/Env.cs
index c2e6c6a..2d230d4 100644
--- a/MidiPlayer/Env.cs
+++ b/MidiPlayer/Env.cs
@@ -6,14 +6,14 @@ namespace MidiPlayer {
     public class Env {
 
         ///////////////////////////////////////////////////////////////////////////////////////////////
-        // static Fields
+        // static Fields [nouns, noun phrases]
 
         static string soundFontDir = "Music";
 
         static string midiFileDir = "Music";
 
         ///////////////////////////////////////////////////////////////////////////////////////////////
-        // static Properties [noun, adjective] 
+        // static Properties [noun, noun phrase, adjective] 
 
         public static string SoundFontDir {
             get {
diff --git a/MidiPlayer/EventQueue.cs b/MidiPlayer/EventQueue.cs
index 0087d85..611d830 100644
--- a/MidiPlayer/EventQueue.cs
+++ b/MidiPlayer/EventQueue.cs
@@ -15,7 +15,7 @@ public class Map<K, V> : Dictionary<K, V> {
     public class EventQueue {
 
         ///////////////////////////////////////////////////////////////////////////////////////////////
-        // static Fields
+        // static Fields [nouns, noun phrases]
 
         static Map<int, Queue<Data>> queueMap = new Map<int, Queue<Data>>();
 
@@ -28,7 +28,7 @@ static EventQueue() {
         }
 
         ///////////////////////////////////////////////////////////////////////////////////////////////
-        // public static Methods [verb]
+        // public static Methods [verb, verb phrases]
 
         public static void Enqueue(int idx, Data value) {
             queueMap[idx].Enqueue(value);
@@ -45,7 +45,7 @@ public static Data Dequeue(int idx) {
     public class Data {
 
         ///////////////////////////////////////////////////////////////////////////////////////////////
-        // Properties [noun, adjective] 
+        // Properties [noun, noun phrase, adjective] 
 
         int prog;
 
@@ -54,7 +54,7 @@ public class Data {
         int vol;
 
         ///////////////////////////////////////////////////////////////////////////////////////////////
-        // Properties [noun, adjective] 
+        // Properties [noun, noun phrase, adjective] 
 
         public int Prog {
             get => prog - 1;
diff --git a/MidiPlayer/Log.cs b/MidiPlayer/Log.cs
index 92b41ad..a87bbae 100644
--- a/MidiPlayer/Log.cs
+++ b/MidiPlayer/Log.cs
@@ -9,12 +9,12 @@ namespace MidiPlayer {
     public static class Log {
 
         ///////////////////////////////////////////////////////////////////////////////////////////////
-        // static Fields
+        // static Fields [nouns, noun phrases]
 
         static Logger logger = LogManager.GetCurrentClassLogger();
 
         ///////////////////////////////////////////////////////////////////////////////////////////////
-        // public static Methods [verb]
+        // public static Methods [verb, verb phrases]
 
         public static void Fatal(string target) {
             LogEventInfo _event = new LogEventInfo(LogLevel.Fatal, logger.Name, target);
diff --git a/MidiPlayer/PlayList.cs b/MidiPlayer/PlayList.cs
index 07ee6a9..82c1b09 100644
--- a/MidiPlayer/PlayList.cs
+++ b/MidiPlayer/PlayList.cs
@@ -8,7 +8,7 @@ namespace MidiPlayer {
     public class PlayList {
 
         ///////////////////////////////////////////////////////////////////////////////////////////////
-        // Fields
+        // Fields [nouns, noun phrases]
 
         List<string> targetList = new List<string>();
 
@@ -22,7 +22,7 @@ public PlayList() {
         }
 
         ///////////////////////////////////////////////////////////////////////////////////////////////
-        // Properties [noun, adjective] 
+        // Properties [noun, noun phrase, adjective] 
 
         public bool Ready {
             get => targetList.Count == 0 ? false : true;
@@ -46,7 +46,7 @@ public string Next {
         }
 
         ///////////////////////////////////////////////////////////////////////////////////////////////
-        // public Methods [verb]
+        // public Methods [verb, verb phrases]
 
         public void Add(string target) {
             targetList.Add(target);
diff --git a/MidiPlayerTests/PrivateObject.cs b/MidiPlayerTests/PrivateObject.cs
index a197f4d..9106eaf 100644
--- a/MidiPlayerTests/PrivateObject.cs
+++ b/MidiPlayerTests/PrivateObject.cs
@@ -9,7 +9,7 @@ namespace MidiPlayer {
     public class PrivateObject {
 
         ///////////////////////////////////////////////////////////////////////////////////////////////
-        // Fields
+        // Fields [nouns, noun phrases]
 
         private readonly object obj;
 
@@ -21,7 +21,7 @@ public PrivateObject(object obj) {
         }
 
         ///////////////////////////////////////////////////////////////////////////////////////////////
-        // public Methods [verb]
+        // public Methods [verb, verb phrases]
 
         public object Invoke(string methodName, params object[] args) {
             var _type = obj.GetType();
diff --git a/MidiPlayerTests/SynthTests.cs b/MidiPlayerTests/SynthTests.cs
index 6fb4ea8..14b08a1 100644
--- a/MidiPlayerTests/SynthTests.cs
+++ b/MidiPlayerTests/SynthTests.cs
@@ -73,14 +73,14 @@ public void GetTrackNameTest3() {
         public void TestInitialize() {
             Synth.SoundFontPath = "../data/OmegaGMGS2.sf2";
             Synth.MidiFilePath = "../data/Cmon_v1.mid";
-            Synth.OnMessage += (IntPtr data, IntPtr evt) => {
+            Synth.Playbacking += (IntPtr data, IntPtr evt) => {
                 return Synth.HandleEvent(data, evt);
             };
-            Synth.OnStart += () => {
+            Synth.Start += () => {
             };
-            Synth.OnEnd += () => {
+            Synth.Ended += () => {
             };
-            Synth.OnUpdate += (object sender, PropertyChangedEventArgs e) => {
+            Synth.Updated += (object sender, PropertyChangedEventArgs e) => {
             };
             playSong();
             Sleep(3000);
@@ -92,7 +92,7 @@ public void TestCelean() {
         }
 
         ///////////////////////////////////////////////////////////////////////////////////////////////
-        // private Methods [verb]
+        // private Methods [verb, verb phrases]
 
         async void playSong() {
             try {