*Extract from VDI 2083 Part 9.1: "This guidline provides definitions of the terms "compatibility with the required cleanliness" and "cleanroom compatibility" and, based on these definitions, the classification and procedures serving to establish the suitability of equipment and air-handling components for use in environments whose air cleanliness and other parameters are assessed in accordance with technical rules (e.g. ISO 14644-1). For the purpose of this guideline, the classification is based on the particle emission.