DDS15 — Clarification of resource management

I don't think that it is explicitly stated anywhere in this spec that each DataWriter and each DataReader maintains its own set of samples. Samples are not maintained by Publishers, Subscribers. It is implied in several places, e.g. the fact that RESOURCE_LIMITS applies to DataWriter and DataReader and not to Publisher and Subscriber. It took me a while to figure this out. It is possible for a Publisher to have more than one DataWriter with the same topic, and a Subscriber to have more than one DataReader with the same topic. The semantics of DataReader.take, for instance, are unclear unless it is understood that each DataReader has its own samples. Evidently a take operation on one DataReader does not disturb the samples of another DataReader with the same Publisher and Topic. Please clarify the specification in this regard. Figure 2-1 and accompanying text would be one place.