ISO 14644-48 offers, for example, very comprehensive guidance for approval and qualification of cleanrooms. Another highlight of ISO 14644-4 is a systematic compilation of all the determinations having to be agreed between customer and supplier during design and development of a cleanroom system. It is condensed into a comprehensive checklist covering 12 subject areas with a grand total of 151 items! If the design activities are cross-checked with its help, it is almost impossible that something of importance has been overseen!