query: # rowing competition classes
  SELECT ?item ?itemLabel ?itemShortName ?itemDescription ?ageclassLabel ?genderLabel ?weightclassLabel ?boatclassLabel ?boatclassShortName WHERE {
    ?item wdt:P31 wd:Q22936940; wdt:P641/wdt:P279* wd:Q159354; wdt:P1813 ?itemShortName .
    OPTIONAL { ?item p:P2094 [ ps:P2094 ?ageclass; pq:P1013 wd:Q185836 ] }
    OPTIONAL { ?item p:P2094 [ ps:P2094 ?gender; pq:P1013 wd:Q48277 ] }
    OPTIONAL { ?item p:P2094 [ ps:P2094 ?weightclass; pq:P1013 wd:Q11423 ] }
    OPTIONAL { ?item p:P2094 [ ps:P2094 ?boatclass; pq:P1013 wd:Q26211803 ] . ?boatclass wdt:P1813 ?boatclassShortName }
    SERVICE wikibase:label { bd:serviceParam wikibase:language 'en' }
  }