§ 101. With respect to the facts of the case before it, the Supreme Court affirmed the Federal Circuit's en banc rejection of an application for a patent on a method of stabilizing cost inputs in the energy industry by hedging price rises against decreases. The Court held that the investment strategy set forth in the application was an "abstract idea," making it ineligible under that exception to the general subject-matter areas listed in the Patent Act. The Supreme Court's decision in Bilski v. Kappos affirmed but sharply qualified the Federal Circuit's 2008 en banc decision in In re Bilski. The decision announced a "machine-or-transformation" test of patent eligibility that, if it had been accepted as the exclusive for process patents, would have made ineligible many business-method patents granted in the last decade. Although the Supreme Court rejected its exclusive use, the test is still important as a "useful and important clue" for determining patent eligibility of claimed process inventions. Under this test: first, processes that transform an article from one state or thing to another are patent eligible regardless of whether their use requires a machine. Processes involving transformation of abstract financial data, such as that claimed in machine format in State Street, are probably patent ineligible. Second, processes that do not make patent-eligible transformations are patent eligible only if they are claimed to be carried out with a "particular machine." It appears that a programmed general-purpose digital computer is not a particular machine, for this purpose. It is unclear from Bilski whether a particular machine must be novel and nonobvious, and specially adapted for carrying out the new process. The Supreme Court's decision in Parker v. Flook seems to call for that, but the Bilski court did not choose to opine on this point at that time. The majority opinion in In re Bilski refused to hold business methods categorically ineligible on any ground. Judge Mayer's dissent, however, seconded by Judges Dyk's and Linn's concurring opinion, insisted that the US patent system is limited to technology and therefore it excludes trade and business expedients. Judge Mayer equated the US Constitution's limitation of patent grants to the "useful arts" to a limitation to technology, relying on case law stating that technology is the modern equivalent of useful arts. In November 2007, the United States Internal Revenue Service proposed rules that would require tax filers who paid a license fee