This International Standard provides guidance for the selection, use and interpretation of results from application of biological indicators when used in the development, validation and routine monitoring of sterilization processes. This International Standard applies to biological indicators for which International Standards exist. NOTE 1 See, for example, the ISO 11138 series. NOTE 2 The general information provided in this International Standard can have useful application for processes and biological indicators not currently addressed by existing International Standards, e.g., new and developing sterilization processes. This International Standard does not consider those processes that rely solely on physical removal of microorganisms, e.g., filtration. This International Standard is not intended to apply to combination processes using, for example, washer disinfectors or flushing and steaming of pipelines. This International Standard is not intended to apply to liquid sterilization processes.