<http://schema.org/topics>
"checkin,contributor,Facebook Places,features,Foursquare,geolocation,gowalla,grammar,grammar freaks,location lists,Mashable,Media Lists,nouns,prepositions,Social Media,news,verbs"^^<http://www.w3.org/2001/XMLSchema#string>
<http://mashable.com/2010/09/03/social-media-grammar-checkin/>