Screening criteria for explosivity based on measurements in a mini-autoclave were recently proposed. A predictive test of these criteria has now been carried out. It has been necessary to reduce the scope of the screen, but the criteria proposed for detonability and other Class 1 properties have been confirmed. A method has been specified to allow further testing and inter-laboratory studies. To co-ordinate these activities, a working group has been formed. (C) 2001 Elsevier Science Ltd. All rights reserved.