query: SELECT DISTINCT ?item ?itemLabel ?itemDescription ?def (GROUP_CONCAT(DISTINCT CONCAT(?partLabel, COALESCE( CONCAT(" (",?sym,")"),"") ); separator=", ") as ?d)  
  {
  	?item wdt:P2534 ?def .
      ?item p:P527 ?st . 
      ?st ps:P527 ?part . 
      OPTIONAL { ?st pq:P416 ?sym } 
  	SERVICE wikibase:label { bd:serviceParam wikibase:language "en"
                             . ?part rdfs:label ?partLabel . ?item rdfs:label ?itemLabel .
                              ?item schema:description ?itemDescription
                             }
  }
  GROUP BY ?item ?itemLabel ?itemDescription ?def
  ORDER BY ?itemLabel 