Message flow in a conversation

According to the specification, it is allowed in the BPMN conversation diagram to model message exchanges between participants using message flows. (See: Business Process Model and Notation (BPMN), version 2.0.)

Message flow between Participants in a BPMN conversation diagram (BPMN 2.0)

Thus, the ARIS connection type message flow (Participant message flow Participant) is available in the BPMN conversation diagram (BPMN 2.0).