Thanks for pointing out this obvious error. All doc references changed from RDF Class (which was just copied from DCAT) to OWL Class with link to the OWL syntax spec, see commit https://github.com/w3c/dxwg/commit/8145dec094340ebdbb12e29aa9443b9107b05f3b.
Rob please review.
The Issue raiser (@riccardoAlbertoni) accepts the change, the relevant PR is merged and it was a trivial editorial one anyway so I'm closing.
Recall that closing issues is to be done by chairs.
Closing after a week's listing as "due for closing" in Plenary 2019-08-27