The U.S. Food and Drug Administration (FDA) has released lists of reference biological products regulated by the Center for Drug Evaluation and Research and the Center for Biologics Evaluation and Research. The lists, referred to as the “Purple Book,” “include the date a biological product was licensed under 351(a) of the PHS [Public Health Service] Act and whether FDA evaluated the biological product for reference product exclusivity under section 351(k)(7) of the PHS Act.” This will enable users to determine whether a licensed biological product “has been determined by FDA to be biosimilar to or interchangeable with a reference biological product.” When FDA begins to approve biosimilars, they will be included in the Purple Book. See FDA Purple Book, September 9, 2014.