doc update, ROS message accessibility depends on RMW implementation.

rcl/include/rcl/client.h

@@ -227,9 +227,9 @@ rcl_client_get_default_options(void);
  * but calling rcl_send_request() at the same time as non-thread safe client
  * functions is not, e.g. calling rcl_send_request() and rcl_client_fini()
  * concurrently is not allowed.
- * Before calling rcl_send_request() the message can change and after calling
- * rcl_send_request() the message can change, but it cannot be changed during
- * the `send_request` call.
+ * The message cannot change during the rcl_send_request() call.
+ * Before calling rcl_send_request() the message can change but after calling
+ * rcl_send_request() it depends on RMW implementation behavior.
  * The same `ros_request`, however, can be passed to multiple calls of
  * rcl_send_request() simultaneously, even if the clients differ.
  * The `ros_request` is unmodified by rcl_send_request().

rcl/include/rcl/publisher.h

@@ -300,9 +300,9 @@ rcl_return_loaned_message_from_publisher(
  * calling rcl_publish() at the same time as non-thread safe publisher
  * functions is not, e.g. calling rcl_publish() and rcl_publisher_fini()
  * concurrently is not allowed.
- * Before calling rcl_publish() the message can change and after calling
- * rcl_publish() the message can change, but it cannot be changed during the
- * publish call.
+ * The message cannot change during the rcl_publish() call.
+ * Before calling rcl_publish() the message can change but after calling
+ * rcl_publish() it depends on RMW implementation behavior.
  * The same `ros_message`, however, can be passed to multiple calls of
  * rcl_publish() simultaneously, even if the publishers differ.
  * The `ros_message` is unmodified by rcl_publish().

rcl/include/rcl/service.h

@@ -308,9 +308,9 @@ rcl_take_request(
  * allowed, but calling rcl_send_response() at the same time as non-thread safe
  * service functions is not, e.g. calling rcl_send_response() and
  * rcl_service_fini() concurrently is not allowed.
- * Before calling rcl_send_response() the message can change and after calling
- * rcl_send_response() the message can change, but it cannot be changed during
- * the rcl_send_response() call.
+ * The message cannot change during the rcl_send_response() call.
+ * Before calling rcl_send_response() the message can change but after calling
+ * rcl_send_response() it depends on RMW implementation behavior.
  * The same `ros_response`, however, can be passed to multiple calls of
  * rcl_send_response() simultaneously, even if the services differ.
  * The `ros_response` is unmodified by rcl_send_response().

rcl_action/include/rcl_action/action_client.h

@@ -291,9 +291,9 @@ rcl_action_server_is_available(
  *
  * The ROS goal message given by the `ros_goal_request` void pointer is always
  * owned by the calling code, but should remain constant during execution of this
- * function. i.e. Before and after calling rcl_action_send_goal_request() the
- * `ros_goal_request` message can change, but it cannot be changed during the call to
- * rcl_action_send_goal_request().
+ * function. i.e. The message cannot change during the rcl_action_send_goal_request() call.
+ * Before calling rcl_action_send_goal_request() the message can change but after calling
+ * rcl_action_send_goal_request() it depends on RMW implementation behavior.
  * The same `ros_goal_request` can be passed to multiple calls of this function
  * simultaneously, even if the action clients differ.
  *
@@ -346,9 +346,9 @@ rcl_action_send_goal_request(
  * If the take is successful, this function will populate the fields of `ros_goal_response`.
  * The ROS message given by the `ros_goal_response` void pointer is always
  * owned by the calling code, but should remain constant during execution of this
- * function. i.e. Before and after calling rcl_action_send_goal_response() the
- * `ros_goal_response` message can change, but it cannot be changed during the call to
- * rcl_action_send_goal_response().
+ * function. i.e. The message cannot change during the rcl_action_send_goal_response() call.
+ * Before calling rcl_action_send_goal_response() the message can change but after calling
+ * rcl_action_send_goal_response() it depends on RMW implementation behavior.
  *
  * <hr>
  * Attribute          | Adherence
@@ -481,9 +481,9 @@ rcl_action_take_status(
  *
  * The ROS message given by the `ros_result_request` void pointer is always
  * owned by the calling code, but should remain constant during execution of this
- * function. i.e. Before and after calling rcl_action_send_result_request() the
- * `ros_result_request` message can change, but it cannot be changed during the call to
- * rcl_action_send_result_request().
+ * function. i.e. The message cannot change during the rcl_action_send_result_request() call.
+ * Before calling rcl_action_send_result_request() the message can change but after calling
+ * rcl_action_send_result_request() it depends on RMW implementation behavior.
  * The same `ros_result_request` can be passed to multiple calls of this function
  * simultaneously, even if the action clients differ.
  *
@@ -536,9 +536,9 @@ rcl_action_send_result_request(
  * If the take is successful, this function will populate the fields of `ros_result_response`.
  * The ROS message given by the `ros_result_response` void pointer is always
  * owned by the calling code, but should remain constant during execution of this
- * function. i.e. Before and after calling rcl_action_take_result_response() the
- * `ros_result_response` message can change, but it cannot be changed during the call to
- * rcl_action_take_result_response().
+ * function. i.e. The message cannot change during the rcl_action_take_result_response() call.
+ * Before calling rcl_action_take_result_response() the message can change but after calling
+ * rcl_action_take_result_response() it depends on RMW implementation behavior.
  *
  * If allocation is required when taking the result, e.g. if space needs to
  * be allocated for a dynamically sized array in the target message, then the