single value constraint
['Acharts.co artist ID', 'Wikidata property for an identifier that does not imply notability', "Identifiers for artists whose songs and albums only charted in Germany cannot be found on the weekly chart pages, as such pages have been disabled for the German charts since 2008. However, they can be found through the website's search function or through links on the relevant song and album pages.", 'Acharts.co chart ID', 'single value constraint']