diff --git a/doc/qbk/00_main.qbk b/doc/qbk/00_main.qbk
index 2560fc6..5f0ae6b 100644
--- a/doc/qbk/00_main.qbk
+++ b/doc/qbk/00_main.qbk
@@ -29,8 +29,6 @@
 [template beastconceptslink[id term][@boost:/libs/beast/doc/html/beast/concepts/[id].html [term]]]
 [template mqttlink[id text][@https://docs.oasis-open.org/mqtt/mqtt/v5.0/os/mqtt-v5.0-os.html#_Toc[id] [text]]]
 
-[def __ASIO_PER_OP_CANCELLATION__ [@boost:/doc/html/boost_asio/overview/core/cancellation.html Per-Operation Cancellation]]
-
 [def __CompletionToken__ [@boost:/doc/html/boost_asio/reference/asynchronous_operations.html#boost_asio.reference.asynchronous_operations.completion_tokens_and_handlers CompletionToken]]
 [def __ExecutionContext__ [reflink2 ExecutionContext ExecutionContext]]
 [def __StreamType__ [reflink2 StreamType StreamType]]
@@ -38,7 +36,12 @@
 
 [def __Boost__ [@https://www.boost.org/ Boost]]
 [def __Asio__ [@boost:/libs/asio/index.html Boost.Asio]]
-[def __Self__ [async_mqtt5]]
+[def __ASIO_PER_OP_CANCELLATION__ [@boost:/doc/html/boost_asio/overview/core/cancellation.html Per-Operation Cancellation]]
+[def __POST__ [@boost:doc/html/boost_asio/reference/post.html `boost::asio::post`]]
+[def __CO_SPAWN__ [@boost:/doc/html/boost_asio/reference/co_spawn.html `boost::asio::co_spawn`]]
+[def __USE_AWAITABLE__ [@boost:/doc/html/boost_asio/reference/use_awaitable.html `boost::asio::use_awaitable`]]
+
+[def __Self__ [reflink2 mqtt_client `mqtt_client`]]
 
 [/ MQTT ]
 [def __MQTT__ [@https://mqtt.org/ MQTT]]
@@ -89,6 +92,8 @@
 [def __REASON_CODES__ [reflink2 Reason_codes `Reason Codes`]]
 [def __ERROR_HANDLING__ [reflink2 Error_handling `Error handling`]]
 
+
 [include 01_intro.qbk]
+[include 02_examples.qbk]
 
 [include reference/reference.qbk]
diff --git a/doc/qbk/02_examples.qbk b/doc/qbk/02_examples.qbk
new file mode 100644
index 0000000..d95f403
--- /dev/null
+++ b/doc/qbk/02_examples.qbk
@@ -0,0 +1,32 @@
+[/
+    Copyright (c) 2023 Mireo
+   
+    Distributed under the Boost Software License, Version 1.0. (See accompanying
+    file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+]
+
+[section:async_examples Compatibility with Boost.Asio]
+The __Self__ is built upon __Asio__ and thus follows the same principles.
+This section illustrates the usage of __Self__ async
+functions with different __CompletionToken__.
+
+# [link async_mqtt5.async_examples.callbacks Async functions with callbacks]
+# [link async_mqtt5.async_examples.cpp20_coroutines Async functions with C++20 coroutines]
+
+
+[section:callbacks Async functions with callbacks]
+This example demonstrates how to use __Self__ asynchrous functions with callbacks.
+
+[import ../../example/callbacks.cpp]
+[callbacks_examples]
+[endsect]
+
+[section:cpp20_coroutines Async functions with C++20 coroutines]
+This example demonstrates how to use __Self__ asynchrous functions with C++20 coroutines
+using __USE_AWAITABLE__ and __CO_SPAWN__.
+
+[import ../../example/cpp20_coroutines.cpp]
+[cpp20_coroutines_examples]
+[endsect]
+
+[endsect]
diff --git a/doc/qbk/reference/Error_handling.qbk b/doc/qbk/reference/Error_handling.qbk
index bd3b814..1170ab8 100644
--- a/doc/qbk/reference/Error_handling.qbk
+++ b/doc/qbk/reference/Error_handling.qbk
@@ -20,6 +20,11 @@ may complete with, along with the reasons for their occurrence.
 		with the __CompletionToken__ provided and the corresponding cancellation signal is emitted,
 		the operation will also finish with this error code (see __ASIO_PER_OP_CANCELLATION__).
 	]]
+	[[`boost::asio::no_recovery`] [
+		An non-recoverable error occurred during the attempt by the [reflink2 mqtt_client `mqtt_client`]
+		to establish a connection with the Broker. The cause of this error may be attributed to the connection 
+		related parameters used during the initialization of the [reflink2 mqtt_client `mqtt_client`].
+	]]
 	[[`boost::asio::experimental::error::channel_cancelled`] [
 		This error occurs in scenarios identical to those causing `boost::asio::error::operation_aborted` 
 		error code but it is exclusive to completion handlers associated with [refmem mqtt_client async_receive] calls.
diff --git a/example/callbacks.cpp b/example/callbacks.cpp
new file mode 100644
index 0000000..92dce53
--- /dev/null
+++ b/example/callbacks.cpp
@@ -0,0 +1,114 @@
+//[callbacks_examples
+
+#include <boost/asio/io_context.hpp>
+
+#include <boost/asio/ip/tcp.hpp>
+
+#include <async_mqtt5.hpp>
+
+#include <iostream>
+
+namespace asio = boost::asio;
+
+using stream_type = asio::ip::tcp::socket;
+using client_type = async_mqtt5::mqtt_client<stream_type>;
+/**
+ * This function showcases how to call each asynchronous function
+ * in mqtt_client using callbacks. Note that this example is not
+ * intended for direct execution, as the async_disconnect call
+ * will promptly close the client.
+ */
+void run_with_callbacks(client_type& client) {
+	// Publish an Application Message with QoS 0.
+	client.async_publish<async_mqtt5::qos_e::at_most_once>(
+		"test/mqtt-test", "Hello world!",
+		async_mqtt5::retain_e::no, async_mqtt5::publish_props {},
+		// Callback with signature void (error_code)
+		[](async_mqtt5::error_code ec) {
+			std::cout << "error_code: " << ec.message() << std::endl;
+		}
+	);
+
+	// Publish an Application Message with QoS 1.
+	client.async_publish<async_mqtt5::qos_e::at_least_once>(
+		"test/mqtt-test", "Hello world!",
+		async_mqtt5::retain_e::yes, async_mqtt5::publish_props {},
+		// Callback with signature void (error_code, reason_code, puback_props)
+		[](async_mqtt5::error_code ec, async_mqtt5::reason_code rc, async_mqtt5::puback_props) {
+			std::cout << "error_code: " << ec.message() << std::endl;
+			std::cout << "reason_code: " << rc.message() << std::endl;
+		}
+	);
+
+	// Publish an Application Message with QoS 2.
+	client.async_publish<async_mqtt5::qos_e::exactly_once>(
+		"test/mqtt-test", "Hello world!",
+		async_mqtt5::retain_e::no, async_mqtt5::publish_props {},
+		// Callback with signature (error_code, reason_code, pubcomp_props)
+		[](async_mqtt5::error_code ec, async_mqtt5::reason_code rc, async_mqtt5::pubcomp_props) {
+			std::cout << "error_code: " << ec.message() << std::endl;
+			std::cout << "reason_code: " << rc.message() << std::endl;
+		}
+	);
+
+	// Subscribe to a single Topic.
+	client.async_subscribe(
+		{ "test/mqtt-test", { async_mqtt5::qos_e::exactly_once } }, async_mqtt5::subscribe_props {},
+		// Callback with signature void (error_code, std::vector<reason_code>, suback_props)
+		[](async_mqtt5::error_code ec, 
+			std::vector<async_mqtt5::reason_code> codes, async_mqtt5::suback_props
+		) {
+			std::cout << "subscribe error_code: " << ec.message() << std::endl;
+			std::cout << "subscribe reason_code: " << codes[0].message() << std::endl;
+		}
+	);
+
+	// Receive an Application Message.
+	client.async_receive(
+		// Callback with signature void (error_code, std::string, std::string, publish_props)
+		[] (
+			async_mqtt5::error_code ec, std::string topic,
+			std::string payload, async_mqtt5::publish_props
+		) {
+			std::cout << "topic: " << topic << std::endl;
+			std::cout << "payload: " << payload << std::endl;
+		}
+	);
+
+	// Unsubscribe from the Topic.
+	client.async_unsubscribe("test/mqtt-test", async_mqtt5::unsubscribe_props {},
+		//Callback with signature void (error_code, std::vector<reason_code>, unsuback_props)
+		[](async_mqtt5::error_code ec, 
+			std::vector<async_mqtt5::reason_code> codes, async_mqtt5::unsuback_props
+		) {
+			std::cout << "unsubscribe error_code: " << ec.message() << std::endl;
+			std::cout << "unsubscribe reason_code: " << codes[0].message() << std::endl;
+		}
+	);
+
+	// Disconnect the Client.
+	client.async_disconnect(
+		async_mqtt5::disconnect_rc_e::disconnect_with_will_message,
+		async_mqtt5::disconnect_props {},
+		// Callback with signature void (error_code)
+		[](async_mqtt5::error_code) {}
+	);
+
+}
+
+int main(int argc, char** argv) {
+	asio::io_context ioc;
+
+	// Make an instance of mqtt_client. Establish a TCP connection with the Broker.
+	client_type c(ioc.get_executor(), "");
+
+	c.credentials("test-client", "username", "password")
+		.brokers("mqtt.broker", 1883)
+		.run();
+
+	run_with_callbacks(c);
+
+	ioc.run();
+}
+
+//]
diff --git a/example/cpp20_coroutines.cpp b/example/cpp20_coroutines.cpp
new file mode 100644
index 0000000..d21df63
--- /dev/null
+++ b/example/cpp20_coroutines.cpp
@@ -0,0 +1,190 @@
+//[cpp20_coroutines_examples
+
+#include <boost/asio/as_tuple.hpp>
+#include <boost/asio/co_spawn.hpp>
+#include <boost/asio/detached.hpp>
+#include <boost/asio/io_context.hpp>
+#include <boost/asio/use_awaitable.hpp>
+
+#include <boost/asio/ip/tcp.hpp>
+
+#include <async_mqtt5.hpp>
+
+namespace asio = boost::asio;
+
+using stream_type = asio::ip::tcp::socket;
+using client_type = async_mqtt5::mqtt_client<stream_type>;
+
+/**
+ * An example of a coroutine. It must have a return type of boost::asio::awaitable<T>.
+ * When an asynchronous function is called, the coroutine is suspended.
+ * After the asynchronous operation finishes, the coroutine resumes from the point it was suspended.
+ *
+ * In this example, each asynchronous function is invoked with boost::asio::use_awaitable completion token.
+ * When using this completion token, co_await will throw exceptions instead of returning an error code.
+ * If you do not wish to throw exceptions, refer to the following nothrow_awaitable and nothrow_coroutine() example.
+ */
+asio::awaitable<void> coroutine(client_type& client) {
+	// Publish an Application Message with QoS 0.
+	// The handler signature for this function is void (error_code).
+	// However, when using asio::use_awaitable as a completion token,
+	// the error_code is not returned but thrown as an exception if an error occurrs.
+	co_await client.async_publish<async_mqtt5::qos_e::at_most_once>(
+		"test/mqtt-test", "Hello world!",
+		async_mqtt5::retain_e::yes, async_mqtt5::publish_props {},
+		asio::use_awaitable
+	);
+
+	// Publish an Application Message with QoS 1.
+	// The handler signature for this function is void (error_code, reason_code, puback_props).
+	// With asio::use_awaitable as a completion token, the co_await will return reason_code and puback_props.
+	auto [puback_rc, puback_props] = co_await client.async_publish<async_mqtt5::qos_e::at_least_once>(
+		"test/mqtt-test", "Hello world!",
+		async_mqtt5::retain_e::yes, async_mqtt5::publish_props {},
+		asio::use_awaitable
+	);
+
+	// Publish an Application Message with QoS 2.
+	// The handler signature for this function is void (error_code, reason_code, pubcomp_props).
+	// With asio::use_awaitable as a completion token, the co_await will return reason_code and pubcomp_props.
+	auto [pubcomp_rc, pubcomp_props] = co_await client.async_publish<async_mqtt5::qos_e::exactly_once>(
+		"test/mqtt-test", "Hello world!",
+		async_mqtt5::retain_e::yes, async_mqtt5::publish_props {},
+		asio::use_awaitable
+	);
+
+	auto sub_topic = async_mqtt5::subscribe_topic {
+		"test/mqtt-test", {
+			async_mqtt5::qos_e::exactly_once,
+			async_mqtt5::subscribe_options::no_local_e::no,
+			async_mqtt5::subscribe_options::retain_as_published_e::retain,
+			async_mqtt5::subscribe_options::retain_handling_e::send
+		}
+	};
+
+	// Subscribe to a single Topic.
+	// The handler signature for this function is void (error_code, std::vector<reason_code>, suback_props).
+	// With asio::use_awaitable as a completion token, the co_await
+	// will return std::vector<reason_code> and suback_props.
+	auto [sub_codes, sub_props] = co_await client.async_subscribe(
+		sub_topic, async_mqtt5::subscribe_props {}, asio::use_awaitable
+	);
+
+	// Receive an Application Message.
+	// The co_await call will return std::string (topic), std::string (payload) and publish_props.
+	// Note: the coroutine will be suspended until an Application Message is ready to be received
+	// or an error has occurred. In theory, the coroutine could be suspended indefinitely.
+	// Avoid calling this if you have not successfully subscribed to a Topic.
+	auto [topic, payload, publish_props] = co_await client.async_receive(asio::use_awaitable);
+
+	// Unsubscribe from the Topic.
+	// The handler signature for this function is void (error_code, std::vector<reason_code>, unsuback_props).
+	// With asio::use_awaitable as a completion token, the co_await
+	// will return std::vector<reason_code> and unsuback_props.
+	auto [unsub_codes, unsub_props] = co_await client.async_unsubscribe(
+		std::vector<std::string>{ "test/mqtt-test" }, async_mqtt5::unsubscribe_props {},
+		asio::use_awaitable
+	);
+
+	// Disconnect the Client.
+	// With asio::use_awaitable as a completion token and void (error_code) as the completion signature,
+	// the co_await has nothing to return.
+	co_await client.async_disconnect(
+		async_mqtt5::disconnect_rc_e::disconnect_with_will_message,
+		async_mqtt5::disconnect_props {},
+		asio::use_awaitable
+	);
+
+	co_return;
+}
+
+/**
+ * A modified completion token. Using this completion token instead of asio::use_awaitable
+ * will prevent co_await from throwing exceptions. Instead, co_await will return the error code
+ * along with other values specified in the handler signature.
+ */
+constexpr auto nothrow_awaitable = asio::as_tuple(asio::use_awaitable);
+
+/**
+ * In this coroutine, each asynchronous function is called with nothrow_awaitable completion token.
+ * Unlike the asio::use_awaitable completion token, nothrow_awaitable does not throw an exception
+ * when an error has occurred. Instead, each co_await will return an error_code, similar to
+ * the behavior of using callbacks.
+ */
+asio::awaitable<void> nothrow_coroutine(client_type& client) {
+	async_mqtt5::error_code ec;
+	async_mqtt5::reason_code rc;
+	
+	std::tie(ec) = co_await client.async_publish<async_mqtt5::qos_e::at_most_once>(
+		"test/mqtt-test", "Hello world!",
+		async_mqtt5::retain_e::yes, async_mqtt5::publish_props {},
+		nothrow_awaitable
+	);
+
+	async_mqtt5::puback_props puback_props;
+	std::tie(ec, rc, puback_props) = co_await client.async_publish<async_mqtt5::qos_e::at_least_once>(
+		"test/mqtt-test", "Hello world!",
+		async_mqtt5::retain_e::yes, async_mqtt5::publish_props {},
+		nothrow_awaitable
+	);
+
+	async_mqtt5::pubcomp_props pubcomp_props;
+	std::tie(ec, rc, pubcomp_props) = co_await client.async_publish<async_mqtt5::qos_e::exactly_once>(
+		"test/mqtt-test", "Hello world!",
+		async_mqtt5::retain_e::yes, async_mqtt5::publish_props {},
+		nothrow_awaitable
+	);
+
+	auto sub_topic = async_mqtt5::subscribe_topic{
+		"test/mqtt-test", {
+			async_mqtt5::qos_e::exactly_once,
+			async_mqtt5::subscribe_options::no_local_e::no,
+			async_mqtt5::subscribe_options::retain_as_published_e::retain,
+			async_mqtt5::subscribe_options::retain_handling_e::send
+		}
+	};
+
+	std::vector<async_mqtt5::reason_code> rcs;
+	async_mqtt5::suback_props suback_props;
+	std::tie(ec, rcs, suback_props) = co_await client.async_subscribe(
+		sub_topic, async_mqtt5::subscribe_props {}, nothrow_awaitable
+	);
+
+	std::string topic, payload;
+	async_mqtt5::publish_props publish_props;
+	std::tie(ec, topic, payload, publish_props) = co_await client.async_receive(nothrow_awaitable);
+
+	async_mqtt5::unsuback_props unsuback_props;
+	std::tie(ec, rcs, unsuback_props) = co_await client.async_unsubscribe(
+		std::vector<std::string>{ "test/mqtt-test" }, async_mqtt5::unsubscribe_props {},
+		nothrow_awaitable
+	);
+
+	std::tie(ec) = co_await client.async_disconnect(
+		async_mqtt5::disconnect_rc_e::disconnect_with_will_message,
+		async_mqtt5::disconnect_props {},
+		nothrow_awaitable
+	);
+
+	co_return;
+}
+
+
+int main(int argc, char** argv) {
+	asio::io_context ioc;
+
+	// Make an instance of mqtt_client. Establish a TCP connection with the Broker.
+	client_type c(ioc.get_executor(), "");
+
+	c.credentials("test-client", "username", "password")
+		.brokers("mqtt.broker", 1883)
+		.run();
+
+	asio::co_spawn(ioc.get_executor(), coroutine(c), asio::detached);
+	// or...
+	asio::co_spawn(ioc.get_executor(), nothrow_coroutine(c), asio::detached);
+
+	ioc.run();
+}
+
+//]
diff --git a/include/async_mqtt5/error.hpp b/include/async_mqtt5/error.hpp
index d730c2c..bd6b9a8 100644
--- a/include/async_mqtt5/error.hpp
+++ b/include/async_mqtt5/error.hpp
@@ -161,6 +161,12 @@ public:
 	/// Move constructor.
 	reason_code(reason_code&&) = default;
 
+	/// Copy assignment operator.
+	reason_code& operator=(const reason_code&) = default;
+
+	/// Move assignment operator.
+	reason_code& operator=(reason_code&&) = default;
+
 	/**
 	 * \brief Indication if the object holds a Reason Code indicating an error.
 	 *
diff --git a/include/async_mqtt5/impl/write_op.hpp b/include/async_mqtt5/impl/write_op.hpp
index e14366e..37e1785 100644
--- a/include/async_mqtt5/impl/write_op.hpp
+++ b/include/async_mqtt5/impl/write_op.hpp
@@ -11,7 +11,6 @@ namespace async_mqtt5::detail {
 
 template <typename Owner, typename Handler>
 class write_op {
-	struct on_write_locked {};
 	struct on_write {};
 	struct on_reconnect {};
 
diff --git a/include/async_mqtt5/mqtt_client.hpp b/include/async_mqtt5/mqtt_client.hpp
index 2bc0bb1..6f39b83 100644
--- a/include/async_mqtt5/mqtt_client.hpp
+++ b/include/async_mqtt5/mqtt_client.hpp
@@ -133,7 +133,6 @@ public:
 		detail::sentry_op { _svc_ptr }.perform();
 	}
 
-	// TODO: channel cancel
 	/**
 	 * \brief Cancel all asynchronous operations. This function has terminal effects.
 	 *
@@ -218,7 +217,9 @@ public:
 	 * \param retain The \ref retain_e flag.
 	 * \param props An instance of \__PUBLISH_PROPS\__. 
 	 * \param token Completion token that will be used to produce a
-	 * completion handler, which will be called when the operation completed.
+	 * completion handler. The handler will be invoked when the operation is completed.
+	 * On immediate completion, invocation of the handler will be performed in a manner
+	 * equivalent to using \__POST\__.
 	 *
 	 * \par Handler signature
 	 * The handler signature for this operation depends on the \ref qos_e specified:\n
@@ -250,8 +251,9 @@ public:
 	 *
 	 *	\par Error codes
 	 *	The list of all possible error codes that this operation can finish with:\n
-	 *		- `boost::system::errc::errc_t::success`\n
+	 *		- `boost::system::errc::errc_t::success` \n
 	 *		- `boost::asio::error::operation_aborted` \n
+	 *		- `boost::asio::error::no_recovery` \n
 	 *		- \link async_mqtt5::client::error::pid_overrun \endlink
 	 *		- \link async_mqtt5::client::error::qos_not_supported \endlink
 	 *		- \link async_mqtt5::client::error::retain_not_available \endlink
@@ -300,7 +302,9 @@ public:
 	 * \param topics A list of \ref subscribe_topic of interest.
 	 * \param props An instance of \__SUBSCRIBE_PROPS\__.
 	 * \param token Completion token that will be used to produce a
-	 * completion handler, which will be called when the operation completed.
+	 * completion handler. The handler will be invoked when the operation is completed.
+	 * On immediate completion, invocation of the handler will be performed in a manner
+	 * equivalent to using \__POST\__.
 	 *
 	 * \par Handler signature
 	 * The handler signature for this operation:
@@ -316,7 +320,8 @@ public:
 	 *
 	 *	\par Error codes
 	 *	The list of all possible error codes that this operation can finish with:\n
-	 *		- `boost::system::errc::errc_t::success`\n
+	 *		- `boost::system::errc::errc_t::success` \n
+	 *		- `boost::asio::error::no_recovery` \n
 	 *		- `boost::asio::error::operation_aborted` \n
 	 *		- \link async_mqtt5::client::error::pid_overrun \endlink
 	 *
@@ -357,7 +362,9 @@ public:
 	 * \param topic A \ref subscribe_topic of interest.
 	 * \param props An instance of \__SUBSCRIBE_PROPS\__.
 	 * \param token Completion token that will be used to produce a
-	 * completion handler, which will be called when the operation completed.
+	 * completion handler. The handler will be invoked when the operation is completed.
+	 * On immediate completion, invocation of the handler will be performed in a manner
+	 * equivalent to using \__POST\__.
 	 *
 	 * \par Handler signature
 	 * The handler signature for this operation:
@@ -373,7 +380,8 @@ public:
 	 *
 	 *	\par Error codes
 	 *	The list of all possible error codes that this operation can finish with:\n
-	 *		- `boost::system::errc::errc_t::success`\n
+	 *		- `boost::system::errc::errc_t::success` \n
+	 *		- `boost::asio::error::no_recovery` \n
 	 *		- `boost::asio::error::operation_aborted` \n
 	 *		- \link async_mqtt5::client::error::pid_overrun \endlink
 	 *
@@ -402,7 +410,9 @@ public:
 	 * \param topics List of Topics to unsubscribe from.
 	 * \param props An instance of \__UNSUBSCRIBE_PROPS\__.
 	 * \param token Completion token that will be used to produce a
-	 * completion handler, which will be called when the operation completed.
+	 * completion handler. The handler will be invoked when the operation is completed.
+	 * On immediate completion, invocation of the handler will be performed in a manner
+	 * equivalent to using \__POST\__.
 	 *
 	 * \par Handler signature
 	 * The handler signature for this operation:
@@ -418,7 +428,8 @@ public:
 	 *
 	 *	\par Error codes
 	 *	The list of all possible error codes that this operation can finish with:\n
-	 *		- `boost::system::errc::errc_t::success`\n
+	 *		- `boost::system::errc::errc_t::success` \n
+	 *		- `boost::asio::error::no_recovery` \n
 	 *		- `boost::asio::error::operation_aborted` \n
 	 *		- \link async_mqtt5::client::error::pid_overrun \endlink
 	 *
@@ -458,7 +469,9 @@ public:
 	 * \param topic Topic to unsubscribe from.
 	 * \param props An instance of \__UNSUBSCRIBE_PROPS\__.
 	 * \param token Completion token that will be used to produce a
-	 * completion handler, which will be called when the operation completed.
+	 * completion handler. The handler will be invoked when the operation is completed.
+	 * On immediate completion, invocation of the handler will be performed in a manner
+	 * equivalent to using \__POST\__.
 	 *
 	 * \par Handler signature
 	 * The handler signature for this operation:
@@ -474,7 +487,8 @@ public:
 	 *
 	 *	\par Error codes
 	 *	The list of all possible error codes that this operation can finish with:\n
-	 *		- `boost::system::errc::errc_t::success`\n
+	 *		- `boost::system::errc::errc_t::success` \n
+	 *		- `boost::asio::error::no_recovery` \n
 	 *		- `boost::asio::error::operation_aborted` \n
 	 *		- \link async_mqtt5::client::error::pid_overrun \endlink
 	 *
@@ -506,7 +520,9 @@ public:
 	 * or there is a pending Application Message.
 	 *
 	 * \param token Completion token that will be used to produce a
-	 * completion handler, which will be called when the operation completed.
+	 * completion handler. The handler will be invoked when the operation is completed.
+	 * On immediate completion, invocation of the handler will be performed in a manner
+	 * equivalent to using \__POST\__.
 	 *
 	 * \par Handler signature
 	 * The handler signature for this operation:
@@ -547,7 +563,9 @@ public:
 	 * the Broker of the reason for disconnection.
 	 * \param props An instance of \__DISCONNECT_PROPS\__.
 	 * \param token Completion token that will be used to produce a
-	 * completion handler, which will be called when the operation completed.
+	 * completion handler. The handler will be invoked when the operation is completed.
+	 * On immediate completion, invocation of the handler will be performed in a manner
+	 * equivalent to using \__POST\__.
 	 *
 	 * \par Handler signature
 	 * The handler signature for this operation:
@@ -587,7 +605,9 @@ public:
 	 * See \ref mqtt_client::cancel.
 	 *
 	 * \param token Completion token that will be used to produce a
-	 * completion handler, which will be called when the operation completed.
+	 * completion handler. The handler will be invoked when the operation is completed.
+	 * On immediate completion, invocation of the handler will be performed in a manner
+	 * equivalent to using \__POST\__.
 	 *
 	 * \par Handler signature
 	 * The handler signature for this operation: