title: c# What are these volume changing codes/messages
body: <p>I found this script to change the System sound volume and it works. But what are these constant volume codes called and where can I find a full list of these codes that do more things.</p>
  
  <pre><code>    [DllImport("user32.dll")]
      static extern IntPtr SendMessage(IntPtr hWnd, int Msg, IntPtr wParam, IntPtr lParam);
  
  //Volume codes, or messages, or whatever they are called
  const int VOLUME_MUTE = 0x80000;
  const int VOLUME_DOWN = 0x90000;
  const int VOLUME_UP = 0xA0000;
  
  SendMessage(this.Handle, 0x319, IntPtr.Zero, (IntPtr)VOLUME_UP);
  </code></pre>