BPMN11 — examples in section 10.2.1 Normal Flow (01)

The problem with the use of Link events for synchronizing behaviour is that there also is a need to explicitly state that two link events are the same object. This can be indicated through the use of (directed or undirected) associations, but that still is an indication only; not formalized. Next, use of such "equality associations" has problems with cases where the "same event" occurs both as an end event and a start event, as seen in figure 10.49. Here, the two "B Completed" link events are probably not exactly the same object (with the same id) since they are of different (sub)types.

Such use of link events, which I do indeed consider very useful, should be improved in upcoming versions of BPMN.
Two possible solutions for this could be:
1) Introduce a way of specifying that two flow objects within/across diagrams are "equal"; possibly also allowing equality across start and end events. Could be a particular kind of associons with strong semantics.

see above