My understanding is Nielsen allows 6+ (PPM) and 12+ (Diary) shares for subscribing stations to be published by entities authorized to do so (like RadioInsight). Nielsen subscribers who have access to demos are allowed to show ranks - but not details like share or AQH persons.Nielsen gives (correct me, Huff, if I am wrong!) the 6+ or 12+ for subscribed stations with some exceptions as well as ranking for the top stations in the key demos and cume. They do not provide owner data nor station slogans or format; the sites like Lance's, insert that. (This is why we prefer Lance's site as he knows the real format names better and properly IDs the formats and owners).
Nielsen displays formats on their public releases based on what stations submit via their Station Information Profiles, and in that profile, stations must choose from a set list of formats provided by Nielsen. So with WXBK for example, they choose to be displayed as "Urban Contemporary" in Nielsen reports; there is no option for "Classic Hip Hop," although they could have also chosen "Urban Oldies" or "Rhythmic Oldies." Most industry sites simply use what Nielsen releases, but RadioInsight goes through each station to correct situations like WXBK's, where a more accurate format descriptor may be appropriate.