The DatasetSeries has no properties on its own, only those inherited from the super-classes Resource and Dataset.

The specification says

The following properties of the super-classes dcat:Resource and dcat:Dataset are also available for use

and lists all properties except for:

• distribution (from dcat:Dataset)
• has part (from dcat:Resource)
• in series (from dcat:Resource)

Ommitting in series seems to be an error, because at 12.1 How to specify dataset series says:

Note that a dataset series can also be hierarchical, and a dataset series can be a member of another dataset series.

For distribution and in seriess I am not sure. But if they should not be used by dcat:DatasetSeries, I think it should be stated explicitly and should be explained.