Following the Berkheimer v. HP Inc. Federal Circuit decision, the USPTO has issued guidelines and training material to the Patent Examining Corps distinguishing what was simply known from what was well-understood, routine conventional activity.  An element is not well-understood, routine or conventional unless the Examiner 1) finds Applicant’s statement that an element is well-understood, routine or conventional; 2) cites a court decision noting that an element is well-understood, routine or conventional; 3) cites a publication that demonstrates that an element is well-understood, routine or conventional or 4) takes official notice.  Relating to the third finding, the memo emphasizes that elements are well-understood, routine or conventional when cited in a book, a manual, a review article or other source describing the state of the art as distinguished from what is simply known in a single patent or published.