BPMN 2.0 allows for intermediate events to thow signals, messages, etc.
This means that I should be able to display an 'intermediate event circle' on the edge of the 'task' (subprocess or plain). For example if the subprocess thows an error, timer, message, etc. event. This is illustrated in a BPMN 2.0 diagram, with the intermediate event at the edge of the task. this intermediate event can also act as a source for the sequence flow .whereby. YeD does not make it possible to make graphs, that are described in this BizAgi tutorial
http://elearning.bizagi.com/file.php/7/BPMN_Videos/6_Events/6_Events.html