In vintage photography the most misused terms are CDV ad cabinet card photos. A CDV is always approximately 2.5 by 4" by its very nature from its name, Carte de Visite, meaning visitng card and thus the size. The CDV was followed by and overlapped in popularity by the cabinet card photo. The cabinet card is always 4 by 6". And both the CDV and the cabinet cards are albumen photographs laid on the cards. A CDV cannot be a cabinet card and a cabinet card cannot be a CDV by the very nature of the terms. And cabinet cards first came into use around 1866 which means that no cabinet card photograph is of Civil War vintage.