ISO 14644-3:2005 is a standard that outlines the requirements for the testing of cleanrooms and clean zones. The standard is part of the ISO 14644 series, which covers various aspects of cleanroom technology, including design, construction, and operation. Specifically, ISO 14644-3:2005 focuses on the testing and certification of cleanrooms, providing a framework for evaluating the cleanliness and contamination control of these environments.