Are ROS2 messages guaranteed to be received by a Subscriber in the same order they were published?

According to https://github.com/ros2/ros2/wiki/About-Quality-of-Service-Settings it's possible to vary the QoS settings of History, Depth, Reliability and Durability. However, I can't find any mention anywhere about the *Ordering* of messages. My understanding is that RTPS guarantees that messages are published in the order they are queued but I couldn't work out whether this also means that all subscribers are guaranteed to receive those messages in the same order as well. Moreover, the ROS2 node's callback that is registered to process a message that has been subscribed to on a given topic must also be called in the same order that the message was published (i.e. not necessarily in the same order it was received at least in my understanding..). This is obviously essential for applications such as transmitting audio or video where we most likely want to ensure subscription of all data messages in the same order they were published - possibly with the option of dropping data messages along the way if latency becomes excessive, but nonetheless preserving the chronological ordering in all cases. Another case I want to confirm is whether messages published and subscribed to by ROS2 intra-process nodes (i.e. which do not use the DDS for transmitting the data) are also guaranteed to both publish messages and subscribe to them in the same order. Thanks. -Ed