Many safety management systems are initially developed in a theoretical environment or for ideal situations with implicit and explicit assumptions about the system’s optimal performance, equipment, and human activities. This is often called WORK-AS-IMAGINED and is formally documented in training, procedures, and equipment operating manuals. Differences between the designed performance or WORK-AS-IMAGINED and the realities of how work is actually done (known as ‘work-as-done’) are common.