[DllImport("USER32", EntryPoint="AppendMenuW", SetLastError=true,
              CharSet=CharSet.Unicode, ExactSpelling=true,
              CallingConvention=CallingConvention.Winapi)]
   private static extern int apiAppendMenu( IntPtr MenuHandle, int Flags,
                                            int NewID, String Item );
上面的声明社么意思?apiAppendMenu 为什么要用AppendMenu+api来代替AppendMenu?