Language tags for titles, descriptions and keywords?

[rwingerter55]

Quote from dcat-ap_2.1.1.pdf, page 29:

For free text, e.g. in the cases of titles, descriptions and keywords, the language tag is mandatory.

Note that the example file dcat_ap_de-RefImp_TTL_ADVANCED.ttl does not use language tags for title, description and keywords:

<https://example.com/dataset/d4ce4e6e-ab89-44cb-bf5c-33a162c234de#dataset>
  # Minimalanforderungen DCAT-AP.de
  a dcat:Dataset ;
  dct:title "Badegewässer in Hamburg" ;
  dct:description "Historische Daten der Badegewässer und ihrer Überwachungsmessstellen im Internet." ;

  # Empfohlen gemaeß DCAT-AP.de
  dcat:distribution <https://example.com/resource/de72be51-7910-43ad-9dfc-10797b42cc0b#distribution> ,
                    <https://example.com/resource/a289c289-55c9-410f-b4c7-f88e5f6f4e47#distribution> ;
  dcat:keyword "wasserbelastung", "gewaesserqualitaet", "umweltueberwachung", "wasser", "badestelle" ;