ISO 11138-3:2006 provides specific requirements for test organisms, suspensions, inoculated carriers, biological indicators and test methods intended for use in assessing the performance of sterilization processes employing moist heat as the sterilizing agent. Moist heat as the sterilizing agent is defined in ISO 11138-3:2006 as dry saturated steam. While air-steam mixtures may be used in moist heat sterilization processes, the methods and performance requirements of this part of ISO 11138 might not be applicable for biological indicators used in such processes.