 As of June 2006, for example, Red Hat had developed a portfolio of 10 issued US patents, 1 issued European patent, 163 pending US patent applications, and 33 pending international PCT (Patent Cooperation Treaty) patent applications.Red Hat uses this portfolio to cross license with proprietary software companies so that they can preserve their freedom to operate.Other patent holders are in the business of inventing new "computer implemented inventions" and then commercializing the inventions by licensing the patents to other companies that manufacture the inventions.