diff --git a/src/WebSocketConnection.php b/src/WebSocketConnection.php
index b357aa5..d985608 100644
--- a/src/WebSocketConnection.php
+++ b/src/WebSocketConnection.php
@@ -221,19 +221,33 @@ class WebSocketConnection implements WebSocketInterface
 
     /**
      * {@inheritDoc}
+     * 
+     * @see writeBinary() to write binary frames as opposed to text frames.
      */
     public function write($data)
     {           
         return $this->send(self::OP_FRAME_TEXT, $data);
     }
 
+    /**
+     * Write binary frames.
+     * 
+     * @param string $data
+     * @return bool
+     */
     public function writeBinary($data)
     {           
         return $this->send(self::OP_FRAME_BINARY, $data);
     }
 
     /**
+     * Encode and send a frame.
      * 
+     * @param int $opcode
+     * @param string $data
+     * @param bool $final
+     * @param bool $masked
+     * @return bool
      */
     public function send(int $opcode, string $data, bool $final = true, bool $masked = false)
     {
@@ -245,9 +259,7 @@ class WebSocketConnection implements WebSocketInterface
             'masked' => $masked
         ]);
 
-        $this->outStream->write($frame);
-
-        return true;
+        return $this->outStream->write($frame);
     }
 
     /**
@@ -261,7 +273,10 @@ class WebSocketConnection implements WebSocketInterface
         $this->emit('close', []);        
     }
 
-    public function closeWithReason(string $reason, int $code=1000)
+    /**
+     * {@inheritDoc}
+     */
+    public function closeWithReason(string $reason, int $code=1000): void
     {
         $payload = chr(($code >> 8) & 0xFF) . chr($code & 0xFF) . $reason;
         $this->send(self::OP_CLOSE, $payload);
diff --git a/src/WebSocketInterface.php b/src/WebSocketInterface.php
index ee4dea7..212ca18 100644
--- a/src/WebSocketInterface.php
+++ b/src/WebSocketInterface.php
@@ -16,15 +16,46 @@ interface WebSocketInterface extends ConnectionInterface
     const EVENT_GROUP_JOIN = 'join';
     const EVENT_GROUP_LEAVE = 'leave';
 
+    /**
+     * Close the connection with a reason and code.
+     * 
+     * @param string $reason
+     * @param int $code
+     * @return void
+     */
+    public function closeWithReason(string $reason, int $code=1000): void;
 
-    public function setGroup(?string $name): void;
-
-    public function getGroupName(): ?string;
-
-    public function getGroup(): ?ConnectionGroup;
-
-    public function closeWithReason(string $reason, int $code=1000);
-
+    /**
+     * Get the initial HTTP request sent to the server.
+     * 
+     * @return ServerRequestInterface
+     */
     public function getServerRequest(): ServerRequestInterface;
 
-}
\ No newline at end of file
+    /**
+     * Assign this connection to a connection group. If the connection is already
+     * part of a group, it will leave the current group before joining the new
+     * group.
+     * 
+     * @param null|string $name The group name to join
+     * @return void
+     */
+    public function setGroup(?string $name): void;
+
+    /**
+     * Get the current connection group.
+     * 
+     * @see getGroupName() if you want the name of the group.
+     * 
+     * @return null|ConnectionGroup
+     */
+    public function getGroup(): ?ConnectionGroup;
+
+    /**
+     * Get the name of the current connection group
+     * 
+     * @return null|string
+     */
+    public function getGroupName(): ?string;
+
+}
diff --git a/src/WebSocketMiddleware.php b/src/WebSocketMiddleware.php
index e075edd..3d767f2 100644
--- a/src/WebSocketMiddleware.php
+++ b/src/WebSocketMiddleware.php
@@ -18,6 +18,8 @@ class WebSocketMiddleware implements EventEmitterInterface
 
     const MAGIC = '258EAFA5-E914-47DA-95CA-C5AB0DC85B11';
 
+    const VERSION = 13;
+
     use EventEmitterTrait;
 
     private GroupManager $groupManager;
@@ -32,7 +34,7 @@ class WebSocketMiddleware implements EventEmitterInterface
 
     public function addRoute(string $path, callable $handler, array $allowedOrigins=[]): void
     {
-
+        // TODO implement or remove
     }
 
     public function __invoke(ServerRequestInterface $request, callable $next)
@@ -62,12 +64,14 @@ class WebSocketMiddleware implements EventEmitterInterface
             $this->emit(self::EVENT_CONNECTION, [ $websocket ]);
         //});
 
+        // TODO would it be possible or rather useful for the 'connection' event to set additional response headers to be sent here?
         return new Response(
             Response::STATUS_SWITCHING_PROTOCOLS,
             array(
                 'Upgrade' => 'websocket',
                 'Connection' => 'upgrade',
-                'Sec-WebSocket-Accept' => $handshakeResponse
+                'Sec-WebSocket-Accept' => $handshakeResponse,
+                'Sec-WebSocket-Version' => self::VERSION
             ),
             $stream
         );        
diff --git a/src/WebSocketProtocol.php b/src/WebSocketProtocol.php
index 1c8de35..a1c9ca5 100644
--- a/src/WebSocketProtocol.php
+++ b/src/WebSocketProtocol.php
@@ -125,6 +125,7 @@ class WebSocketProtocol
         $byte0 = ord($frame[0]);
         $decoded['final'] = !!($byte0 & 0x80);
         $decoded['opcode'] = $byte0 & 0x0F;
+
         // Peek at the second byte, holding mask bit and len
         $byte1 = ord($frame[1]);
         $decoded['masked'] = $masked = !!($byte1 & 0x80);
@@ -146,14 +147,16 @@ class WebSocketProtocol
             $header += 4;
         }
 
-        // Now for the masking
+        // Now for the masking, if present.
         if ($masked) {
             $mask = substr($frame, $header, 4);
             $header += 4;
         }
 
-        // Extract and unmask payload
+        // Extract the payload, and unmask it if needed. The mask() function handles
+        // both masking and unmasing as the algorithm uses xor.
         $payload = substr($frame, $header, $len);
+        // TODO check that extracted payload len equals expected len
         if ($masked) {
             $payload = $this->mask($payload, $mask);
             $decoded['mask'] = $mask;
@@ -174,14 +177,17 @@ class WebSocketProtocol
      */
     private function mask(string $payload, string $mask): string
     {
+        // Unpack the payload and mask into byte values
         $payloadData = array_map("ord", str_split($payload,1));
         $maskData = array_map("ord", str_split($mask,1));
+        // TODO check that mask len==4 
 
         $unmasked = [];
         for ($n = 0; $n < count($payloadData); $n++) {
             $unmasked[] = $payloadData[$n] ^ $maskData[$n % 4];
         }
 
+        // Return the masked byte values packed into a string
         return join("", array_map("chr", $unmasked));
     }