Clarify if dataset series is allowed to contain other dataset series

[matthiaspalmer]

How should the statement "tree organised structures are not prohibited" in chapter 18 be interpreted? Is the intention that dataset series are allowed to contain other dataset series? Clearly this is allowed in DCAT as dcat:DatasetSeries is a subclass of dcat:Dataset. However, we believe that allowing it in DCAT-AP3 is another matter.

If this is the case that it is allowed it should be stated much more clearly higher up in the specification as it will affect both portal implementations and editing software complying to DCAT-AP3.