Hi, I was curious as to why shuffling of events with the same time-step isn't optional. From reading the Schedule code, the sub steps with the same time-step (and same ordering) are extracted into a bag and randomised using the shuffle method. In some situations, particularly debugging it might be preferable to retain the order of sub steps from step to step, or even retain the order in which events were scheduled. Would it be possible to just add a flag which is set to indicate if the schedule should be randomised or not, or does something else rely on the assumption of random ordering. Thanks -- Mike This message has been checked for viruses but the contents of an attachment may still contain software viruses, which could damage your computer system: you are advised to perform your own checks. Email communications with the University of Nottingham may be monitored as permitted by UK legislation.