The term lock out tag out (LOTO) refers to a safety procedure that ensures that machinery and energy sources are properly shut off and not unexpectedly / accidentally started up before the completion of maintenance or servicing work. These energy sources could include electrical, mechanical, hydraulic, pneumatic, chemical, radiation and thermal hazards. The point of a LOTO procedure is to identify and isolate a hazard that may cause injury if it were to start up or release stored energy during the maintenance process.