The global oil and gas industry has expended considerable effort developing process safety procedures aimed at preventing major incidents. The upstream oil and gas industry, in response to major incidents, has developed improved process safety key performance indicators (KPIs) to learn from events with less serious outcomes and to manage system performance. Report 456 enables companies to establish effective leading and lagging indicators that assess the health of barriers that manage the risk of process safety events (PSEs), particularly those that could result in a major incident.