Simulation model animations are usually designed to run in compressed time. This sometimes makes it
difficult to follow the flow of entities through the model. Although it is possible to slow significantly the
animation of the model, it would be better to be able to step through the model event by event. To allow
practitioners to debug their models under controlled circumstances, most simulation software packages
have VCR-like controls. These allow the practitioner not only to step through the model but also to fast
forward to the part of the model the practitioner is interested in viewing.